Electrochromic mirrors and devices

ABSTRACT

The present invention relates to electrochromic mirrors and devices whose electrochromic element is composed of an electrochromic solid film and an electrolyte comprising redox reaction promoters and alkali ions and/or protons.

RELATED UNITED STATES PATENT APPLICATION

[0001] This application is a continuation-in-part of United Statespatent application Serial No. 08/238,521, filed May 5, 1994.

BACKGROUND OF THE INVENTION

[0002] 1. Technical Field of the Invention

[0003] The present invention relates to electrochromic devices forcontinuously varying the transmissivity to light suitable for use in,for example, electrochromic rearview mirrors, windows and sun roofs formotor vehicles, manufactured from electrochromic solid films andelectrolytes containing redox reaction promoters and alkali ions and/orprotons.

[0004] 2. Brief Description of the Related Technology

[0005] Prior to the introduction of electro-optic mirrors into theautomotive marketplace, prismatic rearview mirrors were available todrivers of motor vehicles to determine the whereabouts of neighboringmotor vehicles to their rearward surroundings. By using a manual leverlocated on such mirrors, a driver of a motor vehicle, especially at duskor later, would be able to employ a prismatic feature on the mirror tovitiate the effect of headlamp glare (the principal source of incomingelectromagnetic radiation from the rear of the motor vehicle) from thelow beam, and especially high beam, lighting elements of other motorvehicles travelling posterior thereto. Should the lever be flipped tothe nighttime position, the driver would be able to view an image in areflection from a glass-to-air interface on the first surface of themirror. The light reflected from this first surface would exhibitnon-spectral selectivity. That is, the background of any image viewed inthe nighttime position of the prismatic mirror would be a neutral color.Such conventional prismatic mirrors are still used on a majority ofmotor vehicles in the United States today.

[0006] With the advent of electro-optic technology, such aselectrochromic technology, it has become possible to achieve continuousvariability in reflectivity in rearview mirrors for motor vehicles. Thiscontinuous variability has been achieved, for example, through the useof reversibly variable electrochromic devices, wherein the intensity oflight (e.g., visible, infrared, ultraviolet or other distinct oroverlapping electromagnetic radiation) is modulated by passing the lightthrough an electrochromic medium. In such devices, the electrochromicmedium is disposed between two conductive electrodes and undergoeselectrochromism when potential differences are applied across the twoelectrodes.

[0007] Some examples of these prior art electrochromic devices aredescribed in U.S. Pat. No. 3,280,701 (Donnelly); U.S. Pat. No. 3,451,741(Manos); U.S. Pat. No. 3,806,229 (Schoot); U.S. Pat. No. 4,465,339(Baucke); U.S. Pat. No. 4,712,879 (Lynam) (“Lynam I”); U.S. Pat. No.4,902,108 (Byker) (“Byker I”); Japanese Patent Publication JP 57-30,639(Negishi) (“Negishi I”); Japanese Patent Publication JP 57-208,530(Negishi) (“Negishi II”); and I. F. Chang, “Electrochromic andElectrochemichromic Materials and Phenomena”, in NonemissiveElectrooptic Displays, 155-96, A. R. Kmetz and F. K. von Willisen, eds.,Plenum Press, New York (1976).

[0008] Numerous devices using an electrochromic medium wherein theelectrochromism takes place entirely in a liquid solution are known inthe art [see e.g., U.S. Pat. No. 5,128,799 (Byker) (“Byker II”);Donnelly, Manos, Schoot and Byker I; and commonly assigned U.S. Pat. No.5,073,012 (Lynam) (“Lynam II”); U.S. Pat. No. 5,115,346 (Lynam) (“LynamIII”); U.S. Pat. No. 5,140,455 (Varaprasad) (“Varaprasad I”); U.S. Pat.No. 5,142,407 (Varaprasad) (“Varaprasad II”); U.S. Pat. No. 5,151,816(Varaprasad) (“Varaprasad III”); U.S. Pat. No. 5,239,405 (Varaprasad)(“Varaprasad IV”); and commonly assigned co-pending U.S. patentapplication Ser. Nos. 07/935,784 (filed Aug. 27, 1992) and 08/061,742(filed May 17, 1993)]. Typically, these electrochromic devices,sometimes referred to as electrochemichromic devices, aresingle-compartment, self-erasing, solution-phase electrochromic devices.See e.g., Manos, Negishi II, Byker I and Byker II.

[0009] In single-compartment, self-erasing, solution-phaseelectrochromic devices, the intensity of the electromagnetic radiationis modulated by passing through a solution of the color-forming speciesheld in a single-compartment. The color-changing reaction occurs only inthis solution-phase. That is, there is no solid material present in thedevices that has the color-changing reaction in it. During operation ofsuch devices, the solution of the color-forming species is liquid orfluid, although it may be gelled or made highly viscous with athickening agent, and the components of the solution do not precipitate.See e.g., Byker I and Byker II.

[0010] Numerous devices using an electrochromic medium wherein theelectrochromism occurs in a solid layer are also widely described in theart. Among such devices are those that employ electrochromic thin filmtechnology [see e.g., N. R. Lynam, “Electrochromic Automotive Day/NightMirrors”, SAE Technical Paper Series, 870636 (1987); N. R. Lynam, “SmartWindows for Automobiles”, SAE Technical Paper Series, 900419 (1990); N.R. Lynam and A. Agrawal, “Automotive Applications of ChromogenicMaterials”, Large Area Chromogenics: Materials & Devices forTransmittance Control, C. M. Lampert and C. G. Granquist, eds., OpticalEng'g Press, Washington (1990); C. M. Lampert, “Electrochromic Devicesand Devices for Energy Efficient Windows”, Solar Energy Materials, 11,1-27 (1984); Japanese Patent Document JP 58-30,729 (Kamimori) (“KamimoriI”); U.S. Pat. No. 3,521,941 (Deb); U.S. Pat. No. 3,807,832(Castellion); U.S. Pat. No. 4,174,152 (Giglia); Re. 30,835 (Giglia);U.S. Pat. No. 4,338,000 (Kamimori) (“Kamimori II”); U.S. Pat. No.4,652,090 (Uchikawa); U.S. Pat. No. 4,671,619 (Kamimori) (“KamimoriIII”); U.S. Pat. No. 4,702,566 (Tukude); Lynam I and commonly assignedU.S. Pat. No. 5,066,112 (Lynam) (“Lynam IV”) and U.S. Pat. No. 5,076,674(Lynam) (“Lynam V”)].

[0011] In thin film electrochromic devices, an anodic electrochromiclayer and/or a cathodic electrochromic layer, each layer usually madefrom inorganic metal oxides or polymer films, may be separate anddistinct from one another. In contrast to the single-compartment,self-erasing, solution-phase devices referred to supra, these thin filmelectrochromic devices modulate the intensity of electromagneticradiation by passing through the individual anodic electrochromic layerand/or cathodic electrochromic layer.

[0012] In certain thin film electrochromic devices, a thin film layer ofa solid electrochromic material, such as a tungsten oxide-type solidfilm, may be placed in contact with a liquid electrolyte containingredox promoters, such as ferrocene and iodide, and a solvent. See e.g.,Kamimori III. In these electrochromic devices, the intensity ofelectromagnetic radiation is primarily modulated by passing through thesolid electrochromic material. When dimmed to a colored state, thesetungsten oxide-type solid films typically dim to a blue-colored state.

[0013] Having grown accustomed to conventional prismatic rearviewmirrors for motor vehicles, some consumers of motor vehicles may show apreference for rearview mirrors possessing substantial non-spectralselectivity. That is, some consumers may prefer mirrors which present asubstantially gray color when dimmed to a colored state; in other words,a mirror that exhibits a viewing background comparable in spectralreflectivity to that of conventional prismatic mirrors.

[0014] On another note, the reflective element of the mirror is oftenconstructed from silver and is typically situated on the rearmostsurface of the mirror. That is, the reflective element is placed on thesurface of a glass substrate farthest from that surface which firstcomes in contact with incident light. However, such placement hascertain disadvantages. For instance, double imaging is a recognizedproblem in such mirror construction. In addition, in its path toreaching the reflective element of the mirror, incident light must firstpass through each of the glass substrates of the mirror assembly.Therefore, in these mirror constructions, to achieve good opticalperformance, higher quality glass should be used for both substrates.Moreover, these mirror constructions typically require the use of a thinfilm transparent conductive electrode coating on the inward surface ofeach substrate in order to apply a potential to the electrochromicelement. Requiring each substrate of the mirror to be of such higherquality glass and the use of two such transparent conductive electrodesincreases material and production costs. Further, placement of thereflective element on the rearmost surface of the mirror requires anadditional manufacturing step, which also increases production costs.And, such placement increases material and production costs due tonecessary measures taken to protect the reflective element (typically, ahighly reflective material, such as silver or aluminum) againstenvironmental degradation, such as through the use of a paint or thelike. Frequently, lead-based paints have been used for this purpose,thereby presenting environmental concerns.

[0015] It has been suggested and attempts have been made to place thereflective element of the mirror, such as silver, on the inward facingsurface of the rear substrate so as to act as a conductive electrodecoating as well as a reflective element. See e.g., Donnelly, Negishi I,Byker I and Byker II. This configuration is plainly attractive since iteliminates the need for a separate transparent conductive coating on therear substrate, thereby reducing the cost of manufacture.

[0016] In order to function in the dual role of reflective element andconductive electrode, a coating must (1) be electrochemically stable soas not to degrade during operation of the device, (2) remain securelyadhered to the rear substrate to maintain the integrity of the device,and (3) be highly reflective so that the mirror as a whole will have anacceptable level of reflectance. However, no known mirror constructionmeets all of these requirements—for example silver, commonly used as thereflective element in conventional mirror constructions, is highlyreflective but is not electrochemically stable and is difficult toadhere to the surface of a glass substrate. Other materials, such asrhodium or Inconel, which have been used as a combined reflectiveelement and conducting electrode in prior art mirrors are notsufficiently reflective to provide a highly reflective electrochromicmirror. Perhaps for these reasons, the prior art suggestions andattempts have not resulted in any commercially successful electrochromicmirror in which a single coating is used as both reflective element andconducting electrode.

[0017] Electrochromic devices, such as those using a solid filmelectrochromic material, like tungsten oxide, may also exhibitdeleterious performance when exposed to ultraviolet radiation overprolonged periods of time (e.g., conditions typically encountered duringoutdoor weathering). This deleterious performance may be linked to anyof a variety of sources, including a potential propensity forphotochromism to occur.

[0018] On yet another note, displays, indicia and sensors, such asphotosensors, motion sensors, cameras and the like, have heretofore beenincorporated into certain electrochromic mirror constructions [see e.g.,U.S. Pat. No. 5,189,537 (O'Farrell) and U.S. Pat. No. 5,285,060(Larson)]. In these constructions, the reflective element of the mirrorhas been locally removed to create a highly transmissive local window.However, such use of displays and the like positioned behind thereflective element of electrochromic mirrors has been limited. Onereason for this limited use is due to diminished rear vision capabilityin that portion of the reflective element of the mirror which has beenremoved. Moreover, the displays and the like known to date may bedistracting as well as aesthetically non-appealing to the driver and/orpassengers of motor vehicles insofar as they may be visible andobservable within the mirror mounted in the motor vehicles when in theinactivated state. In addition, the known methods of incorporating suchdisplays and the like into mirrors have been only partially successful,labor intensive and economically unattractive from a manufacturingstandpoint.

[0019] Further, although it has been suggested to use semi-transparentreflectors in rearview mirrors [see e.g., U.S. Pat. No. 5,014,167(Roberts) (“Roberts I”) and U.S. Pat. No. 5,207,492 (Roberts) (“RobertsII”)], previous attempts have included the use of dichroic reflectorswhich are complex to design and expensive to fabricate. Also, where useof metallic reflectors has been suggested [see e.g., U.S. Pat. No.4,588,267 (Pastore)], it has been in the context of conventional mirrorssuch as prismatic mirrors. These suggestions fail to recognize theproblems that must be overcome to provide a highly reflecting andpartially transmitting electrochromic rearview mirror.

[0020] Therefore, the need exists for an electrochromic mirror thatprovides substantial non-spectral selectivity when dimmed to a coloredstate, akin to that exhibited by conventional prismatic mirrors when inthe nighttime position, along with continuous variability inreflectivity, ease and economy of manufacture and enhanced outdoorweathering resilience. It would also be desirable, particularly in thisconnection, to have an electrochromic mirror construction that reducesmaterial and manufacturing costs by employing as only one of itssubstrates a high quality glass as a substrate and also as only one ofits electrodes a thin film, substantially transparent conductiveelectrode coating. In addition, it would be desirable for a mirror tohave display-on-demand capability where a display could become activatedto be viewed on demand, and where the display is (1) aestheticallyappealing and not distracting in its inactivated state, and (2) ismanufactured with ease and economy.

SUMMARY OF THE INVENTION

[0021] The present invention meets the needs expressed above concerningthe desirability of a substantially non-spectral selectiveelectrochromic mirror by providing such an electrochromic mirror thatexhibits substantially non-spectral selectivity in the form of asubstantially neutral or neutral gray appearance when dimmed to a colorstate by the introduction of an applied potential. The electrochromicelement of this mirror comprises an electrochromic solid film and anelectrolyte, which itself comprises redox reaction promoters and alkaliions and/or protons.

[0022] Another aspect of the present invention provides a commerciallypracticable electrochromic mirror having a novel construction. Morespecifically, this novel mirror construction provides a layer ofreflective material coated on the inward surface of the second substratewhich also serves as a conductive electrode coating. The layer ofreflective material is overcoated with an electrochromic solid film andmay also be undercoated to promote its adhesion to the substrate.

[0023] This construction employs a higher quality glass for only one ofits substrates and employs for only that substrate made from a higherquality glass a conductive electrode coating that is substantiallytransparent. That is, the construction permits the use of (1) a lowerquality glass as the second or rearmost substrate while maintaining goodoptical performance in the mirror; (2) a higher resistance, and hencemore economical, conductive electrode coating for the first or frontmostsubstrate which is made from a higher quality glass; and (3) only onesubstantially transparent conductive electrode coating (to be used onthe inward surface of the first substrate made from a higher qualityglass), which further reduces material costs incurred in the manufactureof such mirrors.

[0024] In addition, the layer of reflective material in this novelconstruction reduces further still the material and production costsassociated with such mirrors since it serves the additional role of aconductive electrode coating thereby obviating manufacturing costsassociated with a separate substantially transparent conductiveelectrode coating. Moreover, in this construction, the reflectiveelement of the mirror is located within, and protected by, the sealedcavity which forms the electrochromic element of the mirror. Thereflective element of the mirror is thus protected from degradationthrough environmental exposure without having to resort to the use ofprotective materials, such as lead-based overcoating paints or the like.The novel construction of this electrochromic mirror also enhances theresistance of the reflective material to physical, chemical and/orelectrochemical degradation. Further, the construction so provided alsoreduces image separation which can lead to the recognized problem ofdouble imaging.

[0025] In addition, another aspect of the invention provides an “ondemand display” for mirrors, as described hereinafter. The mirrorconstruction referred to supra and described in detail hereinafter,facilitates placement of displays, indicia and sensors and the likebehind the mirror element so that they may be viewed as an “on demanddisplay”.

[0026] As stated supra, the electrochromic mirrors of the presentinvention exhibit a substantially gray appearance when dimmed to acolored state upon the introduction of an applied potential. Thecoloring capability of these mirrors determines the extent to whichglare may be reflected from the mirrors. As with other electrochromicmirrors, this coloring capability may be continuously varied bycontrolling the magnitude, duration and polarity of the appliedpotential introduced thereto. The appearance of the substantially graycolor may be appealing to consumer preferences (especially to certaindrivers of motor vehicles which employ these mirrors) and to commercialdesign and manufacture concerns by virtue of its substantial colorneutrality relative to the color of the housing, casing, structure,machine, instrument or vehicle with which it is to be used. That is,even when dimmed to a colored state, the electrochromic mirrors of thepresent invention are often aesthetically complementary to the color ofthe other component(s) with which they are to be used.

[0027] The electrochromic mirrors of the present invention are suitablefor use as electrochromic rearview mirrors (e.g., truck mirrors,interior and exterior mirrors for motor vehicles), architectural mirrorsor specialty mirrors, like those useful in aeronautical, periscopic ordental and medical applications.

[0028] In addition to electrochromic mirrors, electrochromic devices,such as electrochromic glazings (e.g., architectural glazings, likethose useful in the home, office or other edifice; aeronauticalglazings, such as those which may be useful in aircraft; or vehicularglazings, for instance, windows, like windshields, side windows andbacklights, sun roofs, sun visors or shade bands); electrochromicoptically attenuating contrast filters, such as contrast enhancementfilters, suitable for use in connection with cathode ray tube monitorsand the like; electrochromic privacy or security partitions;electrochromic solar panels, such as sky lights; electrochromicinformation displays; and electrochromic lenses and eye glass, may alsobenefit from that which is described herein, especially wheresubstantially non-spectral selective coloring is desired.

[0029] Thus, the present invention exemplifies an advance in the artthat will become readily apparent and more greatly appreciated by astudy of the detailed description taken in conjunction with the figureswhich follow hereinafter.

BRIEF DESCRIPTION OF THE FIGURES

[0030]FIG. 1 depicts a spectral scan of percent reflectance versuswavelength in nanometers of an electrochromic mirror according to thepresent invention when in its bleached state.

[0031]FIG. 2 depicts a spectral scan of percent reflectance versuswavelength in nanometers of an electrochromic mirror according to thepresent invention when dimmed to a neutral colored state.

[0032]FIG. 3A depicts a perspective view of an electrochromicmirror—i.e., an interior rearview automobile mirror—according to thepresent invention.

[0033]FIG. 3B depicts a cross-sectional view of the electrochromicmirror of FIG. 3A.

[0034]FIG. 4 depicts another cross-sectional view of the electrochromicmirror of FIGS. 3A and 3B.

[0035]FIG. 5 depicts a cross-sectional view of another electrochromicmirror construction according to the present invention. In thisconstruction, a secondary weather barrier 12 has been applied to thejoint at which sealing means 5 joins substrates 2,3.

[0036]FIG. 6 depicts a cross-sectional view of still anotherelectrochromic mirror construction according to the present invention.This mirror construction is similar to the mirror construction of FIG.5, except that an adhesion promoter 11 is coated between substrate 3 andconductive electrode coating 4′.

[0037]FIG. 7 depicts a cross-sectional view of yet anotherelectrochromic mirror construction according to the present invention.

[0038]FIG. 8 depicts a perspective view of an electrochromic mirrorconstructed with an on demand display.

[0039]FIG. 9 depicts a cross-sectional view of an electrochromic mirrorconstructed with an on demand display using a glass cover sheet over thedisplay window in the mirror construction.

[0040]FIG. 10 depicts a cross-sectional view of another electrochromicmirror constructed with an on demand display.

[0041]FIGS. 11A, B and C depict the orientation of the substrates indifferent constructions of the electrochromic mirrors and electrochromicdevices of the present invention. FIG. 11A depicts a perpendiculardisplacement of the first substrate and the second substrate. FIG. 11Bdepicts a lateral displacement and a perpendicular displacement of thefirst substrate and the second substrate. FIG. 11C depicts anarrangement of the first substrate and the second substrate, wherein thedimensions of the length and width of the first substrate are slightlygreater than those of the second substrate. In this arrangement, theperipheral edge of the first substrate extends beyond the peripheraledge of the second substrate.

[0042]FIG. 12 depicts a perspective view of an electrochromic mirrorconstructed with turn signal indicia.

[0043]FIG. 13 depicts a perspective view of a multi-radiuselectrochromic mirror according to the present invention.

[0044]FIGS. 14A and B depict cross-sectional views of electrochromicdevices, which illustrate different seal constructions that may beemployed in accordance with the present invention.

[0045]FIG. 15 is a schematic diagram of a synchronous manufacturingprocess for electrochromic mirrors according to the present invention.

[0046]FIG. 16 is a schematic diagram of a constant pressure controlsystem useful for evaporative deposition of solid electrochromic films.

[0047]FIG. 17 is a plot of percent transmission versus wavelength for acontinuously variable intensity filter fixed to the glass of theelectrochromic window cell for voltages applied to the electrochromicmedium within the range of from about 0 volts to about 1.4 volts. InFIG. 17, solid curve X represents the percent transmission versuswavelength (nm) spectrum for a 600 nm medium-band interference filterhaving a bandwidth of about 40 nm. Curve A represents light transmissionthrough the band pass filter and the electrochromic window cell with nopotential applied. Curve B represents light transmission through theband pass filter and the electrochromic window cell at an appliedpotential of about 0.3 volts. Curve C represents light transmissionthrough the band pass filter and the electrochromic window cell at anapplied potential of about 0.5 volts. Curve D represents lighttransmission through the band pass filter and the electrochromic windowcell at an applied potential of about 0.8 volts. Curve E representslight transmission through the band pass filter and the electrochromicwindow cell at an applied potential of about 1.1 volts. And curve Frepresents light transmission through the band pass filter and theelectrochromic window cell at an applied potential of about 1.4 volts.

[0048] The depictions in these figures are for illustrative purposesonly and are not drawn to scale. Unless otherwise indicated, in thefollowing detailed description of the invention the element numbersdiscussed are descriptive of like elements of all figures.

DETAILED DESCRIPTION OF THE INVENTION

[0049] In accordance with the teaching of the present invention, thereare provided electrochromic mirrors, such as electrochromic rearviewmirrors for a motor vehicle. These mirrors are constructed from a firstsubstantially transparent substrate with a substantially transparentconductive electrode coating on its inward surface and a secondsubstrate, which may or may not be substantially transparent, with aconductive electrode coating, which also may or may not be substantiallytransparent, on its inward surface. Whether the second substrate and theconductive electrode coating thereon are or are not substantiallytransparent will depend on the particular construction of the mirror.

[0050] The first substrate and second substrate may be positioned inspaced-apart relationship with one another, being substantially parallelor substantially tangentially parallel depending upon whether thesubstrates are flat or bent. These substrates may also be laterallydisplaced from, or in a substantially flush relationship with, oneanother. The substrates may also have respective dimensions such thatone of the substrates is sized and shaped to have a slightly greaterlength and width than the other substrate. Thus, when the substrates arepositioned in central alignment with one another, the peripheral edgesof the slightly larger substrate extend beyond the peripheral edges ofthe slightly smaller substrate.

[0051] The mirrors have a layer of reflective material coated eitheronto (a) the rearmost (non-inward) surface of the second substrate,where it serves a single role as a reflective element of the mirror or(b) the inward surface of the second substrate, where it serves a dualrole as a conductive electrode coating and a reflective element of themirror.

[0052] In these mirrors, an electrochromic solid film is coated eitheronto (a) the transparent conductive electrode coating of the firstsubstrate, (b) the layer of reflective material when acting as aconductive electrode coating on the inward surface of the secondsubstrate or (c) the substantially transparent conductive electrodecoating on the inward surface of the second substrate, when the layer ofreflective material is placed on the rearmost (non-inward) surface ofthe second substrate.

[0053] A sealing means is positioned toward the peripheral edge of eachof the first substrate and the second substrate to form a cavity, inwhich is located, either in a liquid-phase or a solid-phase, anelectrolyte comprising redox reaction promoters and alkali ions and/orprotons. In the cavity, the electrolyte is in contact with theelectrochromic solid film (which itself is in contact with a conductiveelectrode coating on the inward surface of one of either the firstsubstrate or second substrate) and a conductive electrode coating (onthe inward surface of the other of the first substrate or secondsubstrate) to form an electrochromic element.

[0054] Finally, a means for introducing an applied potential to theelectrochromic element is also provided to controllably vary the amountof light reflected from the mirror.

[0055] Decreased light transmissivity in the electrochromic devices ofthe present invention (and reflectivity in the electrochromic mirrors)is primarily provided by the color-forming reaction that occurs in theelectrochromic solid film. This electrochromic solid film may be a thinfilm layer of an inorganic transition metal oxide. Stoichiometric andsubstoichiometric forms of transition metal oxides, such as Group IV-B,V-B or VI-B oxides like tungsten oxide, molybdenum oxide, niobium oxide,vanadium oxide, titanium dioxide and combinations thereof, may be used.Other conventional inorganic transition metal oxides, such as thoserecited in Kamimori III, may also be employed. Preferably, however,tungsten oxide or doped tungsten oxide, with suitable dopants includingmolybdenum, rhenium, tin, rhodium, indium, bismuth, barium, titanium,tantalum, niobium, copper, cerium, lanthanum, zirconium, zinc, nickel,and the like, may be used as the electrochromic solid film. A beneficialeffect of the addition of the dopant may be to move the spectralabsorption edge of the doped tungsten oxide coating farther into thevisible range of the electromagnetic spectrum.

[0056] Where doped tungsten oxide is used, the dopant should be presentin a concentration within the range of from about 0.1% (by mole) toabout 20% (by mole) or even greater. Preferred doped tungsten oxidesinclude those where a molybdenum dopant is used within the range ofabout 0.5% (by mole) to about 10% (by mole).

[0057] The electrochromic solid film may be a stack of thin films, suchas a layer of tungsten oxide overcoated and/or undercoated with a thinfilm like silicon dioxide, titanium dioxide, tantalum pentoxide orcerium oxide. Such overcoats and/or undercoats may help promote enhancedadhesion of the tungsten oxide electrochromic solid film to itssubstrate and/or passivate it from the electrolyte which it contacts inthe electrochromic element.

[0058] When the electrochromic solid film comprises a stack of thinfilms, the layers of the multiple layer stack may individually comprisean electrochromic material. For example, a stacked electrochromic solidfilm can be formed by coating an electrochromic layer of molybdenumoxide onto a transparent conductor coated substrate (to a thickness of,for example, about 100 Å to about 3,000 Å), and by overcoating (and/orundercoating) the molybdenum oxide electrochromic layer with anotherelectrochromic solid film layer, such as tungsten oxide having athickness, for example, in the range of about 100 Å to about 5,000 Å.Alternatively, multiple layers of tungsten oxide and layers ofmolybdenum oxide can be used to form a stacked electrochromic solidfilm.

[0059] When evaporating molybdenum oxide, it may be useful tomelt-process the molybdenum oxide powder prior to evaporation. Sincemolybdenum oxide melts at about 795° C., molybdenum oxide powder(typically about 100 mesh) may be placed into a suitable hightemperature resistant, inert evaporation crucible (such as an aluminacrucible) and converted to a solid mass by heating to a temperaturewithin the range of about 850° C. to about 900° C. for a period of timeof about 60 minutes in a high temperature furnace, preferably in aninert atmosphere such as a nitrogen atmosphere. Since molybdenum oxidemelts at a lower temperature (less than about 1,000° C.) compared toother electrochromic metal oxides such as tungsten oxide that melt at atemperature greater than about 1,000° C., molybdenum oxide (andequivalent lower melting metal oxides) may be used as a binder forevaporation of high melt temperature metal oxide powders.

[0060] The thickness of the electrochromic solid film may be within therange of from about 0.05 μm to about 1.0 μm or greater, with about 0.25μm to about 0.75 μm being preferred, and about 0.3 μm to about 0.6 μmbeing more preferred.

[0061] The electrochromic solid film may have a microstructure that isamorphous, crystalline, polycrystalline or combinations thereof. Inelectrochromic devices where the occurrence of photochromism is aconcern, it may be desirable for the electrochromic solid film topossess a microstructure that is at least partially crystalline. Such acrystalline microstructure is believed to minimize the photochromiceffect, which may be deleterious to the operation of the electrochromicdevices. It may also be desirable for the electrochromic solid film topossess a microstructure that is porous. In this connection, it may bedesirable for the electrochromic solid film, such as tungsten oxide ordoped tungsten oxide, to have a density of less than about 90%,preferably less than about 80%, of the density of the bulk oxide.

[0062] The electrolyte useful in the electrochromic element of theelectrochromic mirrors of the present invention should comprise redoxreaction promoters, and alkali ions and/or protons. The electrolyte maybe in a liquid-phase or in a solid-phase.

[0063] The redox reaction promoters of the electrolyte comprise twoindividual species, a metallocene and a phenothiazine used incombination.

[0064] The metallocenes suitable for use as a redox reaction promoter inthe present invention are represented by the following structure:

metallocenes and their derivatives

[0065] wherein R and R₁ may be the same or different, and each may beselected from the group consisting of H; any straight- or branched-chainalkyl constituent having from about 1 carbon atom to about 8 carbonatoms, such as CH₃, CH₂CH₃, CH₂CH₂CH₃, CH(CH₃)₂, C(CH₃)₃ and the like;acetyl; vinyl; allyl; hydroxyl; carboxyl; —(CH₂)_(n)—OH, wherein n maybe an integer in the range of 1 to about 8; —(CH₂)_(n)—COOR₂, wherein nmay be an integer in the range of 1 to about 8 and R₂ may be anystraight- or branched-chain alkyl constituent having from about 1 carbonatom to about 8 carbon atoms, hydrogen, lithium, sodium,

[0066] wherein n′ may be an integer in the range of 2 to about 8, or

[0067] wherein n′ may be an integer in the range of 2 to about 8;—(CH₂)_(n)—OR₃, wherein n may be an integer in the range of 1 to about 8and R₃ may be any straight- or branched-chain alkyl constituent havingfrom about 1 carbon atom to about 8 carbon atoms,

[0068] or —(CH₂)_(n)—N⁺(CH₃)₃ X⁻, wherein n may be an integer in therange of 1 to about 8 and X may be Cl⁻, Br⁻, I⁻, ClO₄ ⁻ or BF₄ ⁻; and

[0069] M_(e) is Fe, Ni, Ru, Co, Ti, Cr and the like.

[0070] The phenothiazines suitable for use as a redox reaction promoterin the present invention include, but are not limited to, thoserepresented by the following structure:

phenothiazines

[0071] wherein R₄ may be selected from the group consisting of H; anystraight- or branched-chain alkyl constituent having from about 1 carbonatom to about 10 carbon atoms; phenyl; benzyl; —(CH₂)₂—CN; —(CH₂)₂—COCH;

[0072] integer in the range of 2 to about 8;

[0073] wherein R₂ may be any straight- or branched-chain alkylconstituent having from about 1 carbon atom to about 8 carbon atoms; and

[0074] R₅, R₆, R₇, R₈, R₉, R₁₀, R₁₁, R₁₂ may be selected from H, Cl, Br,CF₃, CH₃, NO₂, COOH, SCH₃, OCH₃, O₂CCH₃ or

[0075] and

[0076] R₄ and R₁₂, when taken together, form a ring with six atoms (fiveof which being carbon) having a carbonyl substituent on one of thecarbon atoms.

[0077] Preferred among phenothiazines II is phenothiazine III asdepicted in the following structure:

phenothiazine

[0078] Other desirable phenothiazines II include:

3-acetoxy-methyl-10H-phenothiazine (“AMPT”) IV

[0079]

2,3-dihydro-3-keto-1H-pyrido[3, 2, 1-k1]phenothiazine (“C-PT”) V

[0080]

2-acetyl-phenothiazine (“APT”) VI

[0081] An example of a desirable quinone for use as a redox promoter inthe present invention is

2-hydroxy-naphthoquinone VII

[0082] Combinations of redox reaction promoters may be selectivelychosen to achieve a desired substantially non-spectral selectivity whenthe electrochromic element (and the mirror in which the electrochromicelement is to function) is dimmed to a colored state.

[0083] The redox reaction promoters may be present in the electrolyte ina total concentration of about 0.005 M to about 0.5 M, with a totalconcentration of about 0.02 M to about 0.1 M being preferred. The ratioof this combination (i.e., total metallocene to total phenothiazine)should be within the range of about 1:1 to about 1:10, with a preferredcombination of redox reaction promoters being ferrocene andphenothiazine (III) in about a 1:2 (by mole) to about a 1:4 (by mole)ratio and, more preferably, having a total concentration of about 0.07 Mto about 0.09 M.

[0084] A source of alkali ions may also be included in the electrolyte.Suitable sources of alkali ions are lithium salts, such as lithiumperchlorate (“LiClO₄”), lithium tetrafluoroborate (“LiBF₄”), lithiumiodide (“LI”), lithium hexafluorophosphate (“LiPF₆”), lithiumhexafluoroarsenate (“LiAsF₆”), lithium styrylsulfonate (“LiSS ”),lithium triflate (“LiCF₃SO₃”), lithium methacrylate, lithium halidesother than LI, such as lithium chloride (“LiCl”), lithium bromide(“LiBr”) and the like, lithium trifluoroacetate (“CF₃COOLi”) andcombinations thereof. Of these, LiClO₄ or combinations of LiClO₄ andLiBF₄ are preferred. These sources of alkali ions may be present in theelectrolyte in a concentration of about 0.01 M to about 1.0 M, with aconcentration of about 0.05 M to about 0.1 M being preferred.

[0085] A source of protons may also be included in the electrolyte, by,for example, incorporating into the electrolyte water [for example, in aconcentration of less than about 5% (v/v), preferably in a concentrationwithin the range of about 0.5% (v/v) to about 2% (v/v)], or byincorporating into the electrolyte organic acids, inorganic acids orother protonic sources suitable for use in conjunction with organicsolvents as are known in the art.

[0086] The electrolyte itself may be in a liquid-phase or a solid-phase,however, where the electrolyte is in a liquid-phase, a suitable solventfor use in the electrolyte may solubilize the redox reaction promotersand alkali ions (and other optional components such as ultravioletstabilizing agents which absorb and/or screen ultraviolet radiation)while remaining substantially inert thereto (as well as to any otheroptional components in the electrolyte). Any material that remains inits liquid form over the range of temperatures to which the devicesmanufactured with the electrolytes of the present invention will likelybe subjected is suitable for use as a solvent in a liquid-phaseelectrolyte [for a non-exhaustive recitation of such solvents, see e.g.,Varaprasad I and Varaprasad III]. Practically speaking, the solvent maybe an organic solvent, preferably a substantially non-aqueous organicsolvent, which is stable to electrolysis and other phenomena likely tobe encountered during the practice of this invention.

[0087] Suitable solvents may be selected from acetonitrile,3-hydroxypropionitrile, methoxypropionitrile, 3-ethoxypropionitrile,2-acetylbutyrolactone, propylene carbonate, ethylene carbonate,glycerine carbonate, tetramethylene sulfone, cyanoethyl sucrose,γ-butyrolactone, 2-methylglutaronitrile, N,N′-dimethylformamide,3-methylsulfolane, glutaronitrile, 3,3′-oxydipropionitrile, methylethylketone, cyclopentanone, cyclohexanone, benzoyl acetone,4-hydroxy-4-methyl-2-pentanone, acetophenone, 2-methoxyethyl ether,triethylene glycol dimethyl ether, 4-ethenyl-1,3-dioxalane-2-one,1,2-butylene carbonate, glycidyl ether carbonates (such as thosecommercially available from Texaco Chemical Company, Austin, Tex.) andcombinations thereof, preferred of which include propylene carbonate,1,2-butylene carbonate, the combination of tetramethylene sulfone andpropylene carbonate and the combination of 1,2-butylene carbonate andpropylene carbonate.

[0088] Where the electrolyte of the present invention is desirably asolid-phase electrolyte, a formulation of starting components may be insitu transformed such as by polymerization reaction through, forinstance, exposure to ultraviolet radiation or application of thermalenergy, to produce a solid electrolyte. In the context of ultravioletradiation activated polymerization, ultraviolet polymerizable components[such as those taught by and described in commonly assigned co-pendingUnited States patent application Ser. Nos. 08/023,675, filed Feb. 26,1993 (now abandoned) (“the '675 application”) and 08/193,557, filed Feb.8, 1994 (“the '557 application”), the disclosures of each of which areincorporated herein by reference] may be used to transform into asolid-phase electrolyte when exposed to ultraviolet radiation.

[0089] Other components may also be added to the electrolyte, with suchcomponents preferably being in solution in liquid-phase electrolytes.These components may include, but are not limited to, ultravioletstabilizing agents, infrared radiation reducing agents, color tintingagents (e.g., dyes or colorants) and combinations thereof. Suitableultraviolet stabilizing agents and color tinting agents are recited inLynam III, the disclosure of which is hereby incorporated herein byreference. For example, a blue-colored dye of the phthalocyanine-type,such as “NEOPEN” 808 (commercially available from BASF Corp.,Parsippany, N.J.), may be added to the electrolyte as a color tintingagent.

[0090] Because many redox reaction promoters show a substantialabsorbance in the ultraviolet region of the electromagnetic spectrumfrom about 250 nm to about 350 nm and the electrochromic solid filmitself may be deleteriously affected by exposure to ultravioletradiation, it is often desirable to shield the redox reaction promotersand electrochromic solid film from ultraviolet radiation. Thus, byintroducing an ultraviolet stabilizing agent to the electrolyte, orusing a solvent which itself acts to absorb ultraviolet radiation, thelifetime of the electrochromic device may be extended. It may beparticularly advantageous to include ultraviolet stabilizing agents inthe electrolyte for electrochromic mirrors and electrochromic deviceswhose intended use may result in exposure to outdoor weatheringconditions, such as that encountered by the exterior of a motor vehicle.

[0091] Although many materials known to absorb ultraviolet radiation maybe employed herein, preferred ultraviolet stabilizing agents include“UVINUL” 400 [2,4-dihydroxy-benzophenone (manufactured by BASF Corp.,Wyandotte, Mich.)], “UVINUL” D 49[2,2′-dihydroxy-4,4′-dimethoxybenzophenone (BASF Corp.)], “UVINUL” N 35[ethyl-2-cyano-3,3-diphenylacrylate (BASF Corp.)], “UWINUL” N 539[2-ethyl hexyl-2-cyano-3,3′-diphenylacrylate (BASF Corp.)], “UVINUL” M40 [2-hydroxy-4-methoxybenzophenone (BASF Corp.)], “UVINUL” M 408[2-hydroxy-4-octoxy-benzophenone (BASF Corp.)], “TINUVIN” P[2-(2H-benzotriazole-2-yl)-4-methylphenyl (manufactured by Ciba GeigyCorp., Hawthorne, N.Y.)], “TINUVIN” 327[2-(3′,5′-di-t-butyl-2′-hydroxyphenyl)-5-chloro-benzotriazole (CibaGeigy Corp.)], “TINUVIN” 328[2-(3′,5′-di-n-pentyl-2′-hydroxyphenyl)-benzotriazole (Ciba GeigyCorp.)], “CYASORB” UV 24 [2,2′-dihydroxy-4-methoxy-benzophenone(manufactured by American Cyanamid Co., Wayne, N.J.)] and combinationsthereof, where a suitable range of the ultraviolet stabilizing agents isfrom about 0.2%(w/v) to about 40% (w/v), with about 5% (w/v) to about15% (w/v) being preferred. The ultraviolet stabilizing agent should bechosen with an eye toward avoiding an adverse affect on performance andelectrolyte function.

[0092] In addition, ultraviolet absorbing interlayers may be coatedonto, or adhered to, the first substrate and/or second substrate,particularly the first substrate, to assist in shielding theelectrochromic element from the degradative effect of ultravioletradiation. Suitable ultraviolet absorbing interlayers include thoserecited in Lynam III.

[0093] Moreover, to assist in extending the lifetime of theelectrochromic device, the electrochromic solid film may be placed ontothe inward surface of the second substrate—i.e., coated onto either thereflective element or the substantially transparent conductive electrodecoating depending on the particular construction. Location of theelectrochromic solid film on the inward surface of the second substratemay be desirable where an electrochromic rearview mirror suitable foruse on the exterior of a motor vehicle is intended to be exposed tooutdoor weathering, including exposure to ultraviolet radiation.

[0094] It may also be desirable to employ ultraviolet absorbing glass orlaminates thereof for the first substrate or for the second substrate inan electrochromic mirror, particularly for the first substrate, or forthe first substrate and/or the second substrate in an electrochromicdevice. Suitable ultraviolet absorbing glass include that which isrecited in Lynam IV. In addition, it may be desirable to employ tinoxide, doped tin oxide, zinc oxide or doped zinc oxide as asubstantially transparent conductive electrode coating on the inwardsurface of the first substrate, ultraviolet stabilizing agents in theelectrolyte, ultraviolet absorbing interlayers, ultraviolet absorbingglass and combinations thereof in conjunction with positioning theelectrochromic solid film on the inward surface of the second substrate.Such constructions, particularly with additional ultraviolet stabilizingagents included in the electrolyte as described supra, facilitatescreening and/or absorption of ultraviolet radiation by the componentsused in the electrochromic mirror or electrochromic device, includingthe first substrate, the conductive electrode coating thereon, and theelectrolyte and its components that are positioned effectively in frontof the potentially ultraviolet sensitive electrochromic solid film.

[0095] Addition of ultraviolet stabilizing agents may be particularlyadvantageous when the electrochromic solid film 7 is coated ontoconductive electrode 4′ on the inward surface of substrate 3. (See FIG.5.) In this construction, the ultraviolet stabilizing agents may act toscreen and/or absorb incident ultraviolet radiation before it reachesthe electrochromic solid film 7. By so doing, the chance of irradiatingthe potentially photochromic or otherwise ultraviolet radiationvulnerable electrochromic solid film 7 may be reduced or evensubstantially eliminated. In contrast, when coated onto substantiallytransparent conductive electrode 4 on the inward surface of substrate 2(see FIG. 4), the electrochromic solid film 7 may be directly irradiatedby any incident ultraviolet light that passes through substrate 2. Theultraviolet screening and/or absorbing affect of the electrolyte, whichin this construction is now positioned behind the electrochromic solidfilm 7, has less of an opportunity to shield the electrochromic solidfilm 7 from incident ultraviolet light (although the electrolyte mayeffectively absorb any ultraviolet light which is reflected from thereflective element on substrate 3).

[0096] Those of ordinary skill in the art may make appropriate choicesamong the various materials available as described herein for thesubstrates, coatings, electrochromic solid films and electrolytecomponents—e.g., redox reaction promoters, sources of alkali ions and/orprotons, solvents, and other components—to prepare electrochromicmirrors and electrochromic devices capable of generating a substantiallynon-spectral selective gray color suitable for the desired application.In addition, while glass is a suitable choice of material from which thesubstrates may be constructed, other materials may be used, such asoptical plastics like acrylic, polycarbonate, polystyrene and allyldiglycol carbonate (commercially available from Pittsburgh Plastic GlassIndustries, Pittsburgh, Pa. under the tradename “CR-39”).

[0097] Reference to the figures will now be made in order to morefaithfully describe the electrochromic devices, particularly theelectrochromic mirrors, of the present invention. With reference toFIGS. 3A, 3B and 4, it may be seen that the electrochromic element 1includes a front substrate 2 and a rear substrate 3, each of which istypically glass. However, as described in detail hereinafter, in certainmirror constructions only the front or first substrate 2 needs to be atleast substantially transparent, and in those constructions the rear orsecond substrate 3 need not be transparent at all. (See FIG. 5.) Infact, substrate 3 may be a polished metal plate, a metal-coated glasssubstrate or a conductive ceramic material.

[0098] By convention, the first substrate 2 (the frontmost or outermostsubstrate) is the substrate of the electrochromic device positionedclosest to any principal source of incoming or incident electromagneticradiation and, in an electrochromic mirror, the second substrate 3 isthe substrate onto which a layer of reflective material 8 is coated. Putanother way, the first substrate 2 is the substrate into which a driverof or passenger in a motor vehicle may first look through to view animage. In an electrochromic device, such as a glazing, a window or a sunroof for a motor vehicle, the first substrate 2 is the substrate exposeddirectly to, and often in contact with, the outdoor environment and isexposed directly to solar ultraviolet radiation.

[0099] Substrates 2,3 should be positioned substantially parallel to oneanother if planar (or positioned substantially tangentially parallel toone another if bent), or as close to parallel (or tangentially parallel)to one another as possible so as to minimize image separation which maylead to double imaging. Double imaging is particularly noticeable whenmirrors are colored to a dimmed state. Double imaging may be furtherminimized in mirror constructions as described hereinafter.

[0100] Onto each of the inward surfaces of substrates 2,3 is coated aconductive electrode coating 4 or 4′. The conductive electrode coatings4,4′ may be constructed from the same material or different materials,including transparent electronic conductors, such as tin oxide; indiumtin oxide (“ITO”); half-wave indium tin oxide (“HW-ITO”); full-waveindium tin oxide (“FW-ITO”); doped tin oxides, such as antimony-dopedtin oxide and fluorine-doped tin oxide; doped zinc oxides, such asantimony-doped zinc oxide and aluminum-doped zinc oxide, with tin oxide,doped tin oxide, zinc oxide or doped zinc oxide being preferred wherelong-term ultraviolet resilience is desired in the device. In certainmirror constructions, the conductive electrode coating 4′ need not besubstantially transparent. Rather, the layer of reflective material thatserves as the reflective element of the mirror (with any other coatingsused to form a thin film stack) may also serve as conductive electrodecoating 4′, thereby allowing a potential to be applied to theelectrochromic element 1. Suitable materials for this layer ofreflective material include metals, such as aluminum, palladium,platinum, titanium, chromium, silver, nickel-based alloys and stainlesssteel, with a high reflector (having a reflectance greater than about70%), like silver or aluminum, being preferred. However, whereresistance to scratching and environmental degradation is a concern, amedium reflector (having a reflectance within the range of about 40% toabout 70%), like chromium, stainless steel, titanium and nickel-basedalloys, is preferred. As an alternative to the use of these metals as areflective element, multi-coated thin film stacks of inorganic oxides,halides, nitrides or the like, or a thin film layer of high indexmaterial may also be used.

[0101] The conductive electrode coatings 4,4′ may be thin films ofmetal, such as silver, aluminum and the like, with a thickness of lessthan about 200 Å, which may be as low as less than about 100 Å, so thatthe conductive electrode coatings 4,4′ are sufficiently conductive yetsufficiently transmissive. It may be desirable to index match a thinfilm of metal through the use of a thin film layer of a transparentmetal oxide, metal nitride, metal halide or the like, such as indiumoxide, zinc oxide, tin oxide, magnesium fluoride, titanium nitride,silicon dioxide, tungsten oxide or titanium dioxide, either as anovercoat or an undercoat to the thin film of metal to assist in reducingits reflectance, and increasing its transmittance, of incident visiblelight [see e.g., commonly assigned U.S. Pat. No. 5,239,406 (Lynam)(“Lynam VI”)].

[0102] For example, a layer of a metal, such as silver, preferablyhaving a thickness of less than about 200 Å and a sheet resistance ofless than about 12 ohms per square (more preferably, less than about 10ohms per square, and most preferably, less than about 8 ohms persquare), may be overcoated with a metal oxide transparent conductor[such as a thin film layer of indium oxide (itself either undoped ordoped with tin to form indium tin oxide)] and/or undercoated with ametal oxide layer [such as a thin film layer of indium oxide (itselfeither undoped or doped with tin to form indium tin oxide)] to form asubstantially transmitting multi-layer transparent conductor on a glasssurface. The sheet resistance of the multi-layer transparent conductingstack is preferably less than about 10 ohms per square, more preferablyless than about 8 ohms per square, and most preferably less than 6 ohmsper square. The transmission of visible light through the multi-layertransparent conductor coated glass substrate (which ordinarily comprisesglass/metal oxide/metal/metal oxide or glass/metal/metal oxide such thatthe outermost metal oxide layer overcoating the thin metal layer servesas a barrier coating to reduce or prevent direct contact between thepotentially electrochemically vulnerable metal layer and anyelectroactive medium, such as an electrochemically active liquid,thickened liquid and the like, that contacts the multi-layer transparentstack) is preferably greater than about 70%, more preferably greaterthan about 80%, and most preferably greater than about 85%.

[0103] Though silver is a preferred metal in such multi-layertransparent conducting stacks, aluminum may also be employed,particularly where the optical design of the multi-layer stack isoptimized to maximize overall light transmission. Also, the outermostovercoating metal oxide layer should be at least somewhat, andpreferably significantly, conducting so as not to form an electricalinsulating overcoat on the metal layer. The sheet resistance for such ametal oxide layer should be less than about 2,000 ohms per square, withless than about 1,000 ohms per square being preferred and less thanabout 500 ohms per square being more preferred. This overcoating metaloxide layer may be any at least partially conducting, substantiallytransparent metal oxide such as tin oxide (doped or undoped), indiumoxide (doped or undoped), zinc oxide (doped or undoped) and cadmiumstannate. The thickness for the overcoating metal oxide layer (as wellas the thickness of any undercoating metal oxide layer) is preferablyless than about 500 Å, more preferably less than about 300 Å, and mostpreferably less than about 200 Å.

[0104] Such multi-layer transparent conducting stacks are preferablydeposited using in-line sputter deposition chambers with either planaror rotary magnetron targets, and with deposition of the metal oxidelayers being achieved either by reactive deposition of an oxide coatingby sputtering from a metal target (or from a conductive, pressed oxidetarget) in an oxygen-rich atmosphere, or by radio-frequency (“RF”)sputtering from an oxide target. An example of a multi-layer transparentconducting stack is glass/ITO/Ag/ITO, with the thickness of the ITOlayers being in the range of about 100 to about 300 Å and the thicknessof the silver layer being in the range of about 80 to about 200 Å.

[0105] An economical electrochromic rearview mirror may be fabricated byusing clear glass as a front substrate, substrate 2, (preferablyconstructed from float glass) which is coated on its inwardly facingsurface with a substantially transmitting, multi-layer transparentconductor comprising at least a thin metal layer overcoated with atransparent conductor metal oxide. For instance, a soda-lime glasssubstrate coated with indium tin oxide (having a thickness of about 150Å)/silver (having a thickness of about 150 Å)/indium tin oxide (having athickness of about 150 Å) may be used for the front substrate, substrate2. The rear substrate, substrate 3, is coated with a metal reflector(such as silver, aluminum, chromium, titanium, nickel-based alloys likeHastelloy, iron-based alloys like stainless steel, and the like), whichalso serves as the electrical conductor on substrate 3. Anelectrochromic medium is disposed between the two confronting inwardlyfacing conductor surfaces. An example of such a construction isglass/indium tin oxide (having a thickness of about 150 Å)/silver(having a thickness of about 150 Å)/indium tin oxide (having a thicknessof about 150 Å)//electrolyte//tungsten oxide (having a thickness ofabout 6,000 Å)/aluminum (having a thickness of about 2,000 Å)/chromium(having a thickness of about 1,000 Å)/glass, which construction iseconomical to manufacture as the total thickness of the metal oxidetransparent conducting ITO layer is only about 300 Å. This totalthickness compares favorably to the use of a half wave or full wave ITOlayer with a thickness of about 1,500 Å or 3,000 Å, respectively.

[0106] The sheet resistance of the conductive electrode coated glasssubstrates 2,3 should be less than about 100 ohms per square, with lessthan about 20 ohms per square being preferred. (However, as described ingreater detail hereinafter, for reasons of economy it may sometimes bepreferable to use substantially transparent conductive electrodes havinga sheet resistance of greater than about 20 ohms per square.) Conductiveelectrode coated glass substrates are available commercially. Forinstance, ITO-coated glass substrates made from a glass substrate havingdeposited thereon a conductive coating of indium oxide that has beendoped with tin oxide may be obtained from Donnelly Corporation, Holland,Michigan. In addition, tin oxide-coated glass substrates, known as“TEC-Glass” products, may be obtained from Libbey-Owens-Ford Co., LOFGlass Division, Toledo, Ohio.

[0107] The “TEC-Glass” products are manufactured by an on-line chemicalvapor deposition process. This process pyrolytically deposits onto clearfloat glass a multi-layer thin film structure, which includes amicroscopically thin coating of fluorine-doped tin oxide (having a finegrain uniform structure) with additional undercoating thin film layersdisposed between the fluorine-doped tin oxide layer and the underlyingglass substrate. This structure inhibits reflected color and increaseslight transmittance. The resulting “TEC-Glass” product is anon-iridescent glass structure having a haze within the range of fromabout 0.1% to about 5%; a sheet resistance within the range of fromabout 10 to about 1,000 ohms per square or greater; a daylighttransmission within the range of from about 77% to about 87%; a solartransmission within the range of from about 64% to about 80%; and aninfrared reflectance at a wavelength of about 10 μm within the range offrom about 30% to about 87%. See e.g., United States patent applicationSer. No. 08/061,742, filed May 17, 1993, the disclosure of which ishereby incorporated herein by reference.

[0108] Examples of the “TEC-Glass” products include “TEC 10” (10 ohmsper square sheet resistance), “TEC 12” (12 ohms per square sheetresistance) and “TEC 20” (20 ohms per square sheet resistance) tinoxide-coated glass. More specifically, “TEC 10”, for instance, is madefrom an on-line pyrolytically-coated float glass, onto which has beencoated a fluorine-doped tin oxide layer containing as an undercoat ananti-iridescence means. This anti-iridescence means includes a doublelayer composed of a layer of silica-silicone deposited onto a layer oftin oxide.

[0109] The specific resistivity of the conductive electrode coatings4,4′ useful in the present invention may be between about 5×10⁻³ toabout 1×10⁻⁶ ohm.centimeter, depending on the material from which theconductive electrode coatings 4,4′ are constructed, and on the method ofdeposition and formation of the conductive electrode coatings 4,4′. Forinstance, where the conductive electrode coatings 4,4′ are ITO, thespecific resistivity is typically within the range of about 1×10⁻⁴ toabout 3×10⁻⁴ ohm.centimeter. And where the conductive electrode coatings4,4′ are doped tin oxide, the specific resistivity is typically withinthe range of about 3×10⁻⁴ to about 5×10⁻³ ohm.centimeter. Where theconductive electrode coating 4′ is a metal, the specific resistivity istypically less than about 5×10⁻⁵ ohm.centimeter. And where theconductive electrode coating 4′ is silver, the specific resistivity istypically less than about 3×10⁻⁵ ohm.centimeter. The thickness of themetal should be such that the sheet resistance of conductive electrodecoating 4′ is less than about 0.75 ohms per square, preferably less thanabout 0.5 ohms per square and more preferably less than about 0.25 ohmsper square. Preferably, the thickness of the metal used for conductiveelectrode coating 4′ should be within the range of about 200 Å to about5,000 Å, with a thickness within the range of 500 Å to about 2,500 Åbeing preferred and a thickness within the range of about 750 Å to about1,500 Å being most preferred.

[0110] The substantially transparent conductive electrode coating 4 onthe inward surface of substrate 2 is preferably highly transmissive inthe visible spectrum; that is, with a light transmittance within therange of at least about 60% to greater than about 80%. Likewise, whenthe conductive electrode coating 4′ on the inward surface of substrate 3is to be highly transmissive, similar high light transmittance isdesirable.

[0111] The conductive electrode coatings 4,4′ should also be highly anduniformly conductive in each direction to provide a substantiallyuniform response when a potential is applied to the electrochromicelement 1. And, the conductive electrode coatings 4,4′ should be inert(physically, chemically and electrochemically inert) to the constituentsof the electrochromic solid film 7 and the electrolyte 6.

[0112] Where the electrochromic solid film 7 is deposited as a coatingonto the inward surface of either of conductive electrode coated glasssubstrates 2,3, it is a barrier coating between whichever of theconductive electrode coatings 4,4′ it is deposited on and theelectrolyte 6, as well as a barrier coating between the conductiveelectrode coatings 4,4′ themselves.

[0113] The electrochromic solid film 7 may be deposited using a varietyof film deposition means including, but not limited to, vacuumdeposition techniques, such as thermal evaporation, electron beamevaporation, sputter deposition, ion plating, laser-assisted deposition,microwave-assisted deposition and ion-assisted deposition; thermalspraying; pyrolytic deposition; chemical vapor deposition (“CVD”),including atmospheric CVD, plasma enhanced CVD, low pressure CVD and thelike; wet chemical deposition, including dip coating, spin coating andspray coating; and thick film methods such as those used in theapplication of pastes and inks. Suitable deposition results may beobtained with wet chemical deposition as taught by and described in U.S.Pat. No. 4,855,161 (Moser); U.S. Pat. No. 4,959,247 (Moser); U.S. Pat.No. 4,996,083 (Moser); U.S. Pat. No. 5,252,354 (Cronin) and U.S. Pat.No. 5,277,986 (Cronin), the disclosures of each of which are herebyincorporated herein by reference.

[0114] It may be beneficial to deposit the electrochromic solid filmusing vacuum deposition, preferably with an electron beam evaporationtechnique where the electrochromic solid film 7 is tungsten oxide and isto be placed in direct contact with, or deposited (for example, with analternate evaporation filament, crucible, boat or an alternate electronbeam gun assembly, or the like) as a layer on, the inward surface ofsubstrate 3, which is already coated with a layer of reflective materialthat serves the dual role as a reflective element and a conductiveelectrode coating 4′.

[0115] The layer of reflective material, which also serves as aconductive electrode coating 4′, with or without any adhesion enhancingundercoat layers (discussed hereinafter), may be deposited on the inwardsurface of substrate 3, with tungsten oxide deposited as an overcoat,without the need to refixture, break vacuum or the like. Thus, it isseen that such a dual purpose reflective element may be deposited withmanufacturing ease and economy. This is particularly so when comparedwith conventional mirror constructions where the reflective element iscoated over the rearmost (non-inward) surface of a substrate (whichitself is coated with a substantially transparent conductive electrodecoating on the opposite, inward surface) in one operation, andthereafter loaded into a vacuum chamber to deposit tungsten oxide ontothe other surface of the substrate, which is coated with a substantiallytransparent conductive electrode.

[0116] When vacuum depositing the electrochromic solid film 7 byevaporation or the like, a backfill pressure in a vacuum chamber withinthe range of about 1×10⁻⁴ torr to greater than about 5×10⁻⁴ torr may beused. This backfill pressure may typically be achieved by evacuating thevacuum chamber to some lower base pressure (e.g., less than about 5×10⁻⁵torr) and then backfilling the vacuum chamber with a gas such asnitrogen, argon, krypton, oxygen, water vapor and the like, orcombinations thereof, to elevate the pressure in the vacuum chamber to adesired backfill pressure. Alternatively, the vacuum chamber may bepumped from atmospheric pressure down to about a pressure within therange of about 1×10⁻⁴ torr to greater than about 5×10⁻⁴ torr, andtungsten oxide, for instance, may then be evaporated onto the desiredsurface of substrates 2,3. It may be desirable during such vacuumdeposition to monitor and to control the pressure within the vacuumchamber using pumps, valves and closed loop controls as is known in thevacuum deposition art.

[0117] It may be useful to maintain a relatively constant backfill gaspressure during evaporative deposition of the inorganic oxide solidelectrochromic film layer, or of other layers such as an adhesionpromoter layer and a reflector layer. For example, when evaporatingtungsten oxide in the presence of a backfill gas pressure at a desiredset backfill pressure, it is usually desirable to first pump the chamberfrom atmospheric pressure to a base pressure of about 0.1 times thedesired backfill pressure. By so doing, the backfill pressure shouldremain constant during deposition and not be perturbed by outgasing fromchamber walls, fixtures and the like.

[0118] In order to achieve a relatively constant backfill pressureduring deposition without expending extra process and cycle time to pumpto 0.1 times the desired backfill pressure, a constant pressure controlsystem, as represented in FIG. 16, may be used. Here, the pressure invacuum chamber 1600 is monitored by pressure transducer 1601 whoseoutput signal is compared to a pressure set point V_(PS) at the input ofdifferential amplifier/gas controller 1602. The output 1603 ofdifferential amplifier/gas controller 1602 is used to operate variablevalve 1604 which will admit gas from gas source 1605 to the vacuumchamber so that the difference between the pressure transducer 1601output and the pressure set point V_(PS) remains constant. The backfillpressure in the chamber is principally established by gas admittancethrough fixed valve 1606. The closed-loop operation of variable valve1604, as described above, serves to decrease the volume of backfill gasadmitted when the chamber pressure (as detected by pressure transducer1601) is determined to rise due to outgasing of water vapor and othergaseous species from the chamber walls, fixtures, evaporant, etc., andto increase admittance of backfill gas again when chamber pumpingdecreases the partial pressure of outgassed species so as to maintain aconstant backfill pressure in the chamber during evaporation.

[0119] With reference to FIG. 4, the conductive electrode coatings 4,4′in the mirror construction so depicted are substantially transparent.Likewise, in the mirror construction depicted in FIG. 7, conductiveelectrode coatings 4,4′ and substrate 3 are substantially transparent.

[0120] With reference to FIG. 5, however, only the conductive electrodecoating 4 of the first substrate 2 in the mirror construction sodepicted need be substantially transparent; that is, the conductiveelectrode coating 4′ need not be substantially transparent. In addition,the second substrate 3 need not be substantially transparent. In thisaspect of the present invention, the layer of reflective material may becoated directly onto the inward surface of the second substrate 3 toserve as the conductive electrode coating 4′ as well.

[0121] Onto one of conductive electrode coatings 4,4′ is deposited acoating of an electrochromic solid film 7, such as an inorganictransition metal oxide, like tungsten oxide. As noted herein, wherephotochromism may be a concern, the electrochromic solid film 7 shouldbe positioned at the inward surface of substrate 3 (which surface iscoated with conductive electrode coating 4′). By so doing, theelectrochromic solid film 7 should benefit from the ultravioletscreening and/or absorbing capabilities of the components of the mirrorpositioned in front of it and closer to incident light.

[0122] Silver or aluminum are suitable choices for conductive electrodecoating 4′ of substrate 3 because either metal may serve as a reflectiveelement for the mirror and metal coatings in general are significantlymore conductive than semiconducting oxides, such as ITO or doped tinoxide. As a consequence of using a thin film of metal as conductiveelectrode coating 4′, the substantially transparent conductive electrodecoating 4 of substrate 2 may be chosen with an eye toward higher sheetresistance, such as, for example, about 40 to about 100 ohms per square.This is desirable because conductive electrode coatings of higher sheetresistance are typically thinner and less expensive than conductiveelectrode coatings of lower sheet resistance. ITO or doped tin oxide aresuitable choices for substantially transparent conductive electrodecoating 4 used in conjunction with a thin film of metal as a reflectiveelement, such as silver or aluminum, that is to serve as conductiveelectrode coating 4′. In addition, the use of such a thin film of metalas conductive electrode coating 4′ permits the conductive strip or clipconnectors (known as “bus bars”) to be reduced in length, even to apoint contact, on conductive electrode coating 4′, rather than beingused about a substantial portion of the periphery. That is, bus bars 9may be attached at only a portion of the thin film of metal and stillapply an adequate potential across the conductive electrode coatings4,4′.

[0123] Moreover, use of the reflective element of the mirror as theconductive electrode coating 4′ is also appealing from a productionstandpoint. Such use reduces material and manufacturing costs since anadditional electrode layer or reflective element need not be provided.In addition, this dual purpose reflective element/conductive electrodecoating is environmentally appealing because it is no longer necessaryto enhance resistance to degradation, such as environmental degradation,by applying a paint overcoat, which may be lead-based. In addition, suchconventional reflective elements located on the rearmost surface of themirror construction are typically opaque, and, as described hereinafter,such opacity may result in additional manufacturing effort should an “ondemand display” be desirable in a particular mirror construction.

[0124] Between the layer of reflective material, typically silver, andthe surface of substrate 3 to which it is applied, may desirably becoated a thin film adhesion enhancing means to act as an adhesionpromoter (“adhesion promoter”). (See FIG. 6.) The adhesion promoter 11enhances long-term adhesion of the layer of reflective material to thesurface of substrate 3. It is known in the art that there are certaindifficulties in adhering a reflective material such as silver to asubstrate such as glass, especially where the reflective material is tobe deposited by a vacuum deposition process such as evaporation. Theadhesion promoter 11 of the present invention overcomes thesedifficulties and provides a practical way of applying a coating whichwill function as a dual purpose reflective element/conductive electrodein an electrochromic mirror.

[0125] Suitable adhesion promoters 11 include thin films of metal andmetal oxides that provide enhanced adhesion over a silver to glassinterface, such as chromium, stainless steel, nickel-based alloys (e.g.,Hastelloy), titanium, monel, nichrome, molybdenum, metal oxides (e.g.,silver oxide, aluminum oxide, indium oxide, indium tin oxide, tin oxide,doped tin oxide, zinc oxide, doped zinc oxide and chromium oxide) andthe like. The use of thin films of metal or conducting metal oxides(such as indium tin oxide and doped tin oxides) as adhesion promoters asdescribed herein is advantageous in view of their low cost (due to therelative simplicity of evaporating metal onto a surface of a substrateto form metal or metal oxide coatings), their electrical conductivitythat augments that of conductive electrode coating 4′, and theirmechanical hardness. In addition, use of such thin films of metal orconducting metal oxides as adhesion promoters which undercoat the layerof reflective material assist in maintaining the conductivity of the busbars 9. This is particularly advantageous in the event a bus bar (e.g.,a clip connector) should pierce through the layer of reflectivematerial, because the adhesion promoter is a conductive material thatsustains electrical continuity.

[0126] An adhesion promoter 11 may be an undercoat of a thin film of asingle metal, a metal oxide, or a combination of a metal and a metaloxide. A method for promoting adhesion of the layer of reflectivematerial to a surface of substrate 3 involves deposition, such as byvacuum evaporation or sputtering of a metal, typically silver, initiallyin an oxygen-rich atmosphere. In this atmosphere, a thin film of silveroxide is applied onto a surface of substrate 3. Then, by progressivelydecreasing the oxygen atmosphere to zero, a progressively decreasedamount of oxide is formed with respect to the metal content in the thinfilm deposited on the substrate 3. Finally, with little to no oxygenremaining in the atmosphere, a thin film of silver may be built-up uponthe previously formed undercoat of its own oxide/gradient oxide to forman adhesion-promoting layer between the surface of substrate 3 and thelayer of reflective material. Likewise, chromium may be depositedinitially as a thin film of chromium oxide in an atmosphere of enhancedpartial pressure of oxygen, followed by deposition of a thin film ofmetallic chromium by depleting the supply of oxygen. Oxygen may beintroduced again to permit the deposition of silver oxide, and finallywith deposition of a thin film of metallic silver following in an inertatmosphere. The substrate may also be heated, such as to a temperaturewithin the range of from about 100° C. to about 500° C. (and preferablywithin the range of from about 150° C. to about 400° C.), duringreactive deposition of metal to form a metal oxide. Heating thesubstrate in this manner may assist reactive formation of the oxide fromthe metal and may further enhance adhesion. Moreover, a metal oxide,such as chromium oxide, silver oxide, aluminum oxide, indium oxide, tinoxide, titanium oxide or tantalum oxide, may be deposited, such asreactively deposited in an oxygen-rich atmosphere, by vacuum deposition(e.g., evaporation to sputtering) to form adhesion promoter 11.

[0127] The adhesion promoter 11 should have a thickness within the rangeof from about 10 Å to about 2,500 Å or greater, with about 50 Å to 1,000Å being preferred.

[0128] Adhesion promoter 11 can be a single thin film coating or a stackof thin film coatings. For example, the inward facing surface ofsubstrate 3 can first be coated with a conducting metal oxide adhesionpromoter coating of indium tin oxide, which in turn is overcoated with ametal adhesion promoter coating of chromium, with this stack in turnbeing overcoated with a reflective coating of silver.

[0129] In addition to mirrors employing an electrochromic solid film,adhesion promoter 11 of the present invention may also be used inmirrors employing other types of electrochromic technology, such aselectrochromic solution technology of the electrochemichromic type(e.g., Byker I, Byker II, Varaprasad I and Varaprasad III). Thus,adhesion promoter 11 may be used to construct electrochromic mirrorscontaining an electrochromic solution in which a single coating or stackof coatings functions as a dual purpose reflective element/conductiveelectrode.

[0130] For some applications, it may be desirable to prevent build-up ofdeposited materials (such as, tungsten oxide and/or silver) at a portionor portions of the inward surface of substrates 2 or 3 inboard from anedge thereof. In this regard, a magnetizable metal mask may be placedover the portion(s) where it is desired to prevent build-up of suchdeposited materials. The magnetizable metal mask may then be held atthat portion of the substrate under a magnetic influence while thematerial is deposited. For example, a magnetizable metal mask may beplaced at the desired location on the inward surface of substrate 3prior to coating the inward surface thereof with an adhesion promoter(e.g. chromium), a layer of reflective material (e.g., silver) and alayer of an electrochromic solid film (e.g., tungsten oxide). A magnetmay be placed on the rearmost surface of substrate 3 behind thatlocation on the inward surface of substrate 3 to ensure that the mask isheld in place. Upon removal of the mask after completion of depositionof the chromium/silver/tungsten oxide stack onto the inward surface ofsubstrate 3, a deposition-free portion of that surface is formed.

[0131] As stated supra, the spaced-apart glass substrates 2,3 have asealing means 5 positioned therebetween to assist in defining theinterpane spacing in which the electrochromic solid film 7 and theelectrolyte 6 are located. The sealing means 5 may be constructed of anymaterial inert (physically, chemically and electrochemically inert) tothe electrochromic solid film 7 and the components of the electrolyte 6,as well as to any other material used in the device. To that end, thesealing means 5 may be chosen from the following materials including,but not limited to, various thermosetting materials, such as epoxyresins and silicones, various thermoplastic materials, such asplasticized polyvinyl butyral, polyvinyl chloride, paraffin waxes,ionomer resins, various inorganic materials and the like. For a furtherrecitation of suitable sealing materials, see commonly assigned U.S.Pat. No. 5,233,461 (Dornan).

[0132] The thickness of the sealing means 5 may vary from about 10 μm toabout 1,000 μm. Preferably, however, this thickness is about 50 μm toabout 100 μm.

[0133] In addition, the sealing means 5 may prevent escape of theelectrolyte 6, when in a liquid-phase, from the electrochromic element 1or penetration of environmental contaminants into the electrolyte,whether in a liquid-phase or in a solid-phase. Of course, when theelectrolyte is in a solid-phase, leakage or seepage of the electrolytefrom the mirror is not a concern, but contamination may be.

[0134] Desirably, the sealing means 5 comprises a polymer seal formed bythe cure of a latent cure adhesive formulation, such as a latent cureepoxy. Such latent cure adhesive formulations, as known in the adhesivesarts, comprise an adhesive system (for example, a latent cure epoxysystem). A latent cure adhesive system is sometimes referred to as aone-package system since it is supplied in an uncured or only partiallycured form in a single package and thus does not require the mixingtogether of two or more components (such as a resin and a separatehardener as is common with many adhesive systems like two-componentepoxy systems). This obviates the need to mix together two or morecomponents when forming the sealing means 5.

[0135] Latent cure epoxies typically have a relatively long pot life(e.g., hours to days at room temperature), and so do not appreciably setup and harden at room temperature. However, when exposed to an elevatedtemperature (which depends on the chosen resin and latent curing agentand typically, for the preferred systems used in this present invention,with the activation temperature being at least about 60° C., and morepreferably at least about 90° C.), they cure rapidly to attain theirintended cure and bond strength. Thus, latent cure epoxies have atemperature of activation, below which substantial cure is notinitiated, but above which relatively rapid cure is achieved. Suchsystems may be advantageously employed as the seal material in theelectrochromic cells of the present invention. Also, latent cureadhesives are particularly amenable to commercial scale manufacture ofelectrochromic devices such as electrochromic rearview mirrors (whetherby silkscreening or by direct dispensing from a needle valve dispenser).These latent cure adhesives have a long pot life so that a batch ofadhesive may be used over many hours of production with the assurancethat the adhesive will not unduly age due to room temperature cure(which can lead to inconsistency and potential unreliability in the sealso formed). These latent cure adhesives allow for ease and economy ofmanufacture since by using such one-package, latent cure systems,silkscreens and dispenser systems will not become clogged or obstructeddue to room temperature-induced hardening of the seal adhesive system,and the viscosity of the adhesive system remains relatively constantthroughout the production day. Clean-up is also facilitated due to areduction and near elimination of prematurely hardened adhesive onsilkscreens or within, for instance, dispenser tubing, needles, and thelike.

[0136] One-package, latent cure adhesive formulations useful in formingthe sealing means 5 may typically include a resin (preferably, an epoxyresin such as EPON Resin 828 commercially available from Shell ChemicalCompany, Houston, Tex.), and a latent curing agent (such as adicyandiamide, a modified-amine, an organic acid anhydride, amicroencapsulated amine, an epoxide adduct encapsulated in a polymerizedpolyfunctional epoxide, and an adipic dihydrazide). Latent curing agentsare commercially available, such as from Air Products and ChemicalsIncorporated, Allentown, Pa. under the tradenames ANCAMINE® 2014AS andANCAMINE® 2014FG. These latent curing agents are modified amines. Otherlatent curing agents, such as imidazole-based systems, may also be used.These imidazole-based latent curing agents are also commerciallyavailable from Air Products and Chemicals Incorporated under thetradenames IMCURE® (such as, IMCURE® AMI-2) and CUREZOL™ (such as,CUREZOL™ 2E4MZ, 1B2MZ, 2PZ, C17Z, 2MZ Azine, 2PHZ-5 and 2MA-OK). Also,latent curing agents are commercially available from AJINOMOTOIncorporated, Teaneck, N.J. under the tradename AJICURE®, examples ofwhich include AJICURE® PN-23 and AJICURE® MY-24. Latent cure adhesives,such as latent cure epoxies, optionally and desirably, include fillers(such as, silica-based fillers like IMSIL A-8, which is commerciallyavailable from UNIM Specialty Minerals Incorporated, Elco, Ill., andcalcium carbonate-based fillers like SS-14066 HUBERCARB OPTIFILL, whichis commercially available from J.M. Huber Corporation, Quincy, Ill.),and coupling agents (useful as adhesion promoters) like the silanecoupling agents listed in Table I below: TABLE I SILANE/ COMMERCIALSUPPLIER CHEMICAL NAME Z6020, Dow CorningN-(2-aminoethyl)-3-amino-propyltri- methoxy silane Z6032, Dow CorningN-[2-vinyl benzylamino-ethyl]-3- aminopropyltrimethoxy silane Z6076, DowCorning 3-chloropropyltrimethoxy silane A187, Union Carbideγ-glycidoxypropyltrimethoxy silane A1100, Union Carbideγ-aminopropyltriethoxy silane A174, Union Carbideγ-methacryloxypropyltrimethoxy silane Aldrich Chemicals2-dichloropropyltrimethoxy silane Aldrich Chemicals diphenyldiethoxysilane Q1-6101, Dow Corning proprietary organic trimethoxy silane

[0137] Coloring agents (such as, carbon black and heavy metal- oriron-based pigments) and spacer beads (such as, glass) may also beincluded. A particularly useful latent cure adhesive formulation for thecommercial production of electrochromic rearview mirrors with goodmanufacturing economics and with excellent double image performanceexhibited by the mated substrates comprises: Parts Per Hundred ComponentType Parts of Resin Type Resin EPON 8281 — Epoxy Latent CuringANCAMINE ® 28 Modified Agent 2014FG Amine Filler Calcium Carbonate 30Coloring Agent Carbon Black  1 Spacer Beads Glass  1

[0138] This latent-cure adhesive formulation may either be silkscreenedto form the sealing means 5 or may be applied using an automatic fluiddispensing system, such as a high speed, computer controlled fluiddispensing system supplied by ASYMTEK, Carlsbad, Calif. under thetradename AUTOMOVE 400, and the like. Use of a latent curing agent(which produces long-term stability at room temperature but rapid cureat elevated temperatures) in the adhesive formulation used to establishthe sealing means 5 is particularly advantageous when using an automaticfluid dispensing system. In such a system, constancy and control of thefluid viscosity is facilitated, and consistency and precision of thebead of fluid adhesive dispensed around the perimeter of the substrateis also facilitated. Latent curing agents are particularly desirablewhen precision dispensing valves are used, such as a rotary positivedisplacement (“RPD”) valve like the DV-06 valve commercially availablefrom ASYMTEK.

[0139] Once the latent cure adhesive is screened or dispensed around theedge perimeter of a substrate, and after the second substrate isjuxtaposed therewith to establish a cell with an interpane spacing, thelatent cure adhesive may be rapidly cured by exposure to elevatedtemperatures, typically greater than about 60° C. Epoxy adhesive systemsthat use ANCAMINE® latent curing agents and that are cured by exposureto a temperature of at least about 110° C. for a period of time of aboutone hour, or less, perform excellently. What's more, the cured sealexhibits resilience when exposed to boiling water for a period of timein excess of 96 hours. The double image performance for suchANCAMINE®-cured mirror cells was also found to be superior to comparabletwo-component epoxy systems in that, during typical production ofelectrochromic rearview mirrors, double imaging measured from cellsusing the latent curing agent to effect a cure to form the sealing means5 was consistently lower than comparably processed electrochromicrearview mirrors which used a two-component epoxy to form the sealingmean 5. Also, the glass transition temperature (T_(g)) for the sealingmean 5 formed by cure of a one-package, latent cure adhesive ispreferably less than about 140° C., more preferably less than about 120°C. and most preferably less than about 100° C.

[0140] One-package adhesive and sealing systems, that are supplied witha latent curing agent already incorporated in the adhesive formulation,are also commercially available. Such one part curing adhesivesincorporate an integral hardener or catalyst and typically include aliquid epoxy resin and a dicyandiamide hardener. Examples include a onepart epoxy adhesive commercially available from A1 Technology,Princeton, N.J., under the tradenames EH7580, ME 7150-SMT or ME7155-ANC; a one part epoxy adhesive commercially available from AmericanCyanamid, Wayne N.J. under the tradename CYBOND 4802; and a one partepoxy commercially available from CHEMREX, Commerce City, Colo., underthe tradename CHEMREX 7459-9772. Also, one part aerobic adhesive andsealing systems, which depend on oxygen or moisture in the air toactivate or achieve cure, may also be used to form the sealing mean 5.An example of such a one part aerobic adhesive and sealing system ismoisture-activated silicone.

[0141] Double image performance in rearview mirrors is greatly assistedby the use of a vacuum-assisted sealing technique. An example of such atechnique is a vacuum bag technique where, spacer means, such as spacerbeads, are disposed across the surfaces of the substrates being mated,and a vacuum is used to better assure substrate to substrate conformity.It is preferable for at least one substrate (usually the first or frontsubstrate) to be thinner than the other, and preferably for at least onesubstrate to have a thickness of 0.075″ or less, with a thickness of0.063″ or less being more preferable, and with a thickness of 0.043″ orless being most preferable. This improvement in double image performanceis particularly desirable when producing convex or multi-radius outsidemirror parts, and when producing large area parts (such as, Class 8heavy truck mirrors), and especially when vacuum backfilling is used intheir production.

[0142] Using a vacuum-assisted sealing technique, an uncured sealingadhesive (with spacer beads optionally included therein) may bedispensed around the periphery of a first substrate. Spacer beads,preferably glass beads capable of withstanding a load, are sprinkledacross a surface of the second substrate and the first substrate isjuxtaposed thereon. This mated assembly is then temporarily affixed (bytemporary clamps, a temporary fixture, and the like), and placed withina vacuum bag (such as, a heavy duty “MYLAR” bag). The bag is thenevacuated to a vacuum using a vacuum pump. Atmospheric pressure nowevenly bears down on the surfaces of the substrates to be mated forcingconformance of the substrates to each other and to the precision glassspacers that are selected to establish the intended interpane spacing.The temporarily-fixed assembly (still within the vacuum bag) and thusunder a pressure of at least 2 lbs./in² is then placed into an ovenwhich is at atmospheric pressure (or into a heated autoclave which maybe at several atmospheres pressure) so that the seal adhesive is causedto cure and to set. This may be performed either with vacuum retained bysealing the bag so as to render it airtight or with the hose to thevacuum pump still attached. Once the seal, typically an epoxy, cures andsets, the conformance of the substrates to the spacer beads and to eachother is retained by the now-cured adhesive seal, even when the vacuumbag is vented and the fabricated part removed.

[0143] For exterior mirrors that have an area of at least about 140 cm²,it is desirable to place at least some rigid spacer means (such asprecision glass beads) at locations within the interpane space betweenthe substrates in the laminate electrochromic cell. Preferably, suchspacer beads are chosen to have a refractive index within the range ofabout 1.4 to about 1.6 so that they optically match the refractive indexof the substrates (typically glass) and the electrolyte. These rigidspacer beads not only assist conformity and uniformity of interpanespacing, but also help maintain the integrity of peripheral seals onexterior rearview mirrors assemblies that use a liquid or thickenedliquid. For instance, the peripheral seal may burst if an installer orvehicle owner presses on the mirror at its center and causes a hydraulicpressure build-up at the perimeter seal due to the compression of thefluid or thickened fluid at the part center. Use of such spacer beads,particularly when located at the center of the part within the interpanespace, are beneficial in this regard whether the exterior rearviewmirror is a flat mirror, convex mirror or multi-radius mirror, and isparticularly beneficial when at least the first or front substrate (thesubstrate touched by the vehicle operator or service installer) isrelatively thin glass, such as with a thickness of about 0.075″ or less.Use of, for example, two substrates, each having a thickness of about0.075″ or less, for exterior rearview mirrors, including large areamirrors of area greater than about 140 cm², has numerous advantagesincluding reduced weight (reduces vibration and facilitates manually-and electrically-actuated mirror adjustment in the mirror housing),better double-image performance, and more accurate bending forconvex/multi-radius parts.

[0144] Also, for the sealing mean 5, it is advantageous to use asomewhat flexible polymer seal material to reduce double imaging frommated substrates, and to improve hot/cold thermal shock performance forassemblies using a solid electrolyte. For example, the sealing mean 5may be a silicone such as, a one component, black, addition curingsilicone polymer system (like those commercially available from LoctiteCorporation, Newington, Conn. under the tradename VISLOX V-205) or aprimerless, one-part, flowable adhesive that develops a strong,self-priming bond to glass (and coated glass) substrates (like thosecommercially available from Dow Corning, Midland, Mich. under thetradename Q3-6611). Alternatively, a thixotropic, one-part siliconeelastomer adhesive, such as X3-6265 commercially available from DowCorning, may be used to form the sealing mean 5. Flexible epoxy resinsmay also be used to form the sealing mean 5.

[0145] Standard epoxy resins based on bisphenol A and commonly usedcuring agents are typically brittle and need to be modified to give atough and flexible cured system. Flexibilization of the resin system maybe internally (commonly referred to as flexibilizing, which may beachieved through the use of long-chain aliphatic amines as parts ofcuring agents; the addition of aminated or carboxylated rubbers; theaddition of carboxy-terminated polyesters; the addition of long-chainorganic compounds containing hydroxyl-functional groups; the use oflong-chain aliphatic epoxide materials including epoxidized oils), andexternally using plasticizers. Internal flexibilization is preferable,such as is achieved when a typical epoxy resin (for example, with anepoxide equivalent weight of about 185) is flexibilized by addition of adifunctional primary amine curing agent, such as polyoxypropylenediamine commercially available from Texaco Chemical Company, Houston,Tex. under the tradename JEFFAMINE™ 400, and the like. Desirably, about25-50 parts of any of the above-noted flexibilizers per hundred parts ofresin may be used. Such flexibilized epoxy systems have a % elongationat break within the range of about 50 to about 150, compared to lessthan about 10, for rigid epoxies. In addition, urethane adhesivesystems, such as FLEXOBOND 431 (which is a clear, two-part urethanesystem, commercially available from Bacon Industries, Watertown, Mass.)may be used.

[0146] optionally, and desirably when oxygen permeable seal materialssuch as silicones are used, a double-seal may be used. In this case, afirst seal (often, the inner seal when silicone and flexible systems areused) is screened/dispensed and a second seal of a different material(often, a rigid epoxy when the first seal is flexible) isscreened/dispensed separately and distinctly from the first seal. Thus,for example, a bead of uncured silicone is screened/dispensed inboard,and around, the perimeter of a substrate, and a bead of uncured epoxy isthen dispensed outboard of the silicone bead and around the edge of thesubstrate. Next, a second substrate is mated with the first substrate sothat the double seal adhesive is sandwiched therebetween, and then bothadhesive seals are cured in an oven to form the desired cured, doubleseal.

[0147] Also, whether the sealing mean 5 is a single seal or a doubleseal, it may be desirable for the seal material to comprise a curedconductive adhesive so that the seal, or at least a portion thereof, mayprovide, in whole or at least in part, an electrical bus bar functionaround the perimeter of a substrate of the assembly. When using such acombined seal and bus bar, care should be taken to avoid electricallyshorting the inward facing surfaces of substrates 2 and 3. To obviatethis, a seal construction, such as that shown in FIG. 14-A, may be used.With reference to FIG. 14-A, substrates 1420 and 1430 are coated ontheir inwardly facing surfaces with electrical conductor electrodes1420′ and 1430′. The substrates 1420, 1430 are mated together with thecompound seal 1420. The compound seal 1450 includes a conducting seallayer 1450A (formed, for example, of a conducting epoxy such as isdescribed below) and a non-conducting, electrically insulating seallayer 1450B (formed, for example, of a conventional, non-conductingepoxy), which serves to insulate the two conducting electrodes fromelectrically shorting via conducting seal layer 1450A. Since thecompound seal 1450 essentially circumscribes the edge perimeter of thepart, the conducting seal layer 1450A (to which electrical potential maybe connected to via the electrical lead 1490) serves as an electricallyconductive bus bar that distributes applied electrical power more evenlyaround and across the electrochromic medium (not shown) sandwichedbetween the substrates 1420 and 1430.

[0148] Where the electrical conductor electrode 1420′, 1430′ on at leastone of the opposing surfaces of the substrates 1420, 1430 is removed (orwas never coated) in the region of the peripheral edge (as shown in FIG.14-B), a unitary conducting seal (as opposed to the compound seal ofFIG. 14-A) may be used. Reference to FIG. 14-B shows the electricallyconducting seal 1450A joining the electrical conductor electrode 1430′on the surface of substrate 1430 to a bare, uncoated surface of opposingsubstrate 1420. Since the contact area of the conducting seal layer1450A to the substrate 1420 is devoid of the electrical conductorelectrode 1420′, the conducting seal layer 1450A does not short theelectrodes 1420′ and 1430′. Conducting seal layer 1450A serves the dualrole of bus bar and seal, yielding economy and ease in devicefabrication and production. Conducting seal layer 1450A may form asingle seal for the cell or may be one of a double seal formed, forexample, when a conventional, non-conducting epoxy is used inboard ofthat conducting seal.

[0149] Such a construction is particularly amenable to devices, such asthose depicted in FIGS. 5 and 6. For instance, in a rearview mirror, afixture can form a mask around the edge substrate perimeter, while anadhesion layer of chromium followed by a reflector layer of aluminumfollowed by an electrochromic layer of tungsten oxide are deposited.Once removed from such a coating fixture, the edges, as masked by thecoating fixture, are uncoated and present a bare glass surface forjoining via a conductive epoxy seal to an opposing transparent conductorcoated substrate. In such a configuration, the conductive seal can serveas a bus bar for the transparent conductor coated substrate it contactswithout shorting to the reflector/adhesion layers on the oppositesubstrate. Preferably, a fast curing, single component, silver filled,electrically conductive epoxy adhesive is used in such a construction,such as is commercially available from Creative Materials Incorporated,Tyngsboro, Mass. under the tradename CMI 106-32A. Alternatively, 102-05Fand 114-11 (also commercially available from Creative MaterialsIncorporated) electrically conductive inks may be used, which aresolvent-resistant, electrically conductive adhesives (with a silvercontent of greater than about 85%, when cured).

[0150] Alternatively, a silver conductor polymer thick film composition,such as the one commercially available from E.I. du Pont de Nemours,Wilmington, Del. under the designation 5025, may be used. Du Pont 5025is a screen-printable conductive ink that has an air dried sheetresistivity of about 12-15 mΩ/square/mil. Thermoset silver inks may alsobe used, and are preferred over the air dried variety in terms ofconductivity and sealing performance. Such thermoset silver inks aresingle-component, epoxy based inks, typically with a silver contentgreater than about 50%, with greater than about 75% being preferred, andare fired by exposure to a temperature of about 150° C. for a period oftime of about one hour. A suitable thermoset conductive epoxy is 5504N,which is commercially available from Du Pont. Also, electricallyconductive adhesives such as AREMCO-BOND 525 (commercially availablefrom Aremco Products, Incorporated, Ossining, N.Y.), may be used.AREMCO-BOND 525 is an electrically conductive adhesive that cures whenfired at a temperature of about 350° F. for a period of time of aboutone hour.

[0151] To enhance the integrity of a long-lasting seal in terms of sealresiliency, any electrochromic solid film 7 deposited toward theperipheral edges of one of the substrates 2,3 may be removed so that aseal may be formed directly between a conductive electrode coating 4 ofsubstrate 2 and a conductive electrode coating 4′ of substrate 3—i.e.,directly between at least a portion of the conductive electrode coatedglass substrates 2,3. This may be accomplished, for example, bydepositing tungsten oxide onto larger sheets of glass and then cuttingsubstrates therefrom. By so doing, the tungsten oxide coating extends tothe cut edge of the substrate. A variety of removal means may then beemployed to remove that portion of the coating from the substrate—up toless than about 2 mm to about 6 mm or thereabouts—inward from theperipheral edges of the substrates. These removal means may includechemical removal, such as with water or with a slightly acidic or basicaqueous solution; physical removal, such as with a blade; laser etching;sandblasting and the like. The conductive electrode coatings 4,4′ at theperipheral edge may also be removed in like fashion along with thetungsten oxide overcoat.

[0152] Alternatively, substrates 2,3 may be pre-cut to a desired sizeand shape prior to depositing an electrochromic solid film 7 thereon.These pre-cut substrates may be loaded into a masking fixture to preventdeposition of the electrochromic solid film 7 a pre-determined distancefrom the edges of the substrates—such as, inward from the edge up toless than about 2 mm to about 6 mm. The masking system may also allowfor small tab-out portions to facilitate electrical connection with theconductive electrode coatings 4,4′ and the electrochromic solid film 7deposited in one and the same deposition operation. Of course, it may bepossible to employ movable fixturing or to break vacuum and rearrangefixtures should tab-outs not be desired.

[0153] Moisture is known to permeate through electrochromic solid films,such as tungsten oxide. Thus, where sealing mean 5 is positionedentirely or partially over the electrochromic solid film 7, a secondaryweather barrier 12 may be advantageously employed about the periphery ofthe joint of the assembled laminate (see FIG. 5) to optimize sealintegrity which may be compromised by such moisture permeation orpermeation of other environmental degradants. Suitable materials for useas a secondary weather barrier 12 include adhesives, such as silicones,epoxies, epoxides and urethanes, which may be ultraviolet curable, roomtemperature curable or heat curable.

[0154] Commercially available adhesives include the cycloalkyl epoxidessold under the “CYRACURE” tradename by Union Carbide Chemicals andPlastics Co., Inc., Danbury, Conn., such as the “CYRACURE” resinsUVR-6100 (mixed cycloalkyl epoxides), UVR-6105(3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate), UVR-6110(3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate) andUVR-6128 [bis-(3,4-epoxycyclohexyl)adipate], and the “CYRACURE” diluentsUVR-6200 (mixed cycloalkyl epoxides) and UVR-6216 (1,2-epoxyhexadecane);those epoxides commercially available from Dow Chemical Co., Midland,Mich., such as D.E.R. 736 epoxy resin (epichlorohydrin-polyglycolreaction product), D.E.R. 755 epoxy resin (diglycidyl ether of bisphenolA-diglycidyl ether of polyglycol) and D.E.R. 732 epoxy resin(epichlorohydrin-polyglycol reaction product), and the NOVOLAC epoxyresins such as D.E.N. 431, D.E.N. 438 and D.E.N. 439 (phenolicepoxides), and those epoxides commercially available from Shell ChemicalCo., Oak Brook, Ill., like the “EPON” resins 825 and 1001F(epichlorohydrin-bisphenol A type epoxy resins).

[0155] Other commercially available adhesives that are particularlywell-suited for use herein as a secondary weather barrier 12 includethose epoxides commercially available under the “ENVIBAR” tradename fromUnion Carbide Chemicals and Plastics Co., Inc., Danbury, Conn., such as“ENVIBAR” UV 1244T (cycloalkyl epoxides).

[0156] A secondary weather barrier 12 may be formed around the sealedjoint between substrates 2,3 at any point of contact between the sealingmean 5 and the electrochromic solid film 7, using in the case ofultraviolet curable adhesives, commercially available curing systems,such as the Fusion UV Curing Systems F-300 B and F-450 [Fusion UV CuringSystems, Buffalo Grove, Ill.], Hanovia UV Curing System [Hanovia Corp.,Newark, N.J.], RC-500 A Pulsed UV Curing System [Xenon Corp., Woburn,Mass.] and a Sunlighter UV chamber fitted with low intensity mercuryvapor lamps and a turntable.

[0157] A source of an applied potential may be introduced to theelectrochromic element 1 of the electrochromic mirror by the electricalleads 10, which may be wire, solder and the like. The electrical leads10 may typically be connected or affixed to bus bars 9, which themselvesmay typically be connected or affixed to the conductive electrodecoatings 4,4′. The bus bars 9 may be constructed from a variety ofconducting materials including metals, alloys, solder such asultrasonically-applied solder (e.g., Cerasolzer™ manufactured by theAsahi Glass Co., Tokyo, Japan), metal ribbon connecters, conductingpolymers (e.g., conducting rubbers and conducting epoxies), conductingfrits, such as silver frits [e.g., silver conductive frit #7713(commercially available from E.I. du Pont de Nemours and Company,Wilmington, Del.)] and the like. A non-exhaustive recitation of suchconducting materials may be found in Lynam IV. Bus bar materials such asconducting silver frits or solders may even overlap onto the cut edge ofthe substrate to facilitate connection of electrical leads in the flushassemblies of the invention.

[0158] An exposed portion of the conductive electrode coatings 4,4′ maybe provided through displacement in opposite directions relative to oneanother—i.e., laterally from, but parallel to, the cavity which iscreated by the substrates 2,3 and the sealing means 5—of the substrates2,3 onto which the bus bars 9 may be affixed or adhered. (See FIG. 11A.)In addition, substrates 2,3 may be off-set to provide an exposed portionof the conductive electrode coatings 4,4′ through displacement inopposite directions relative to one another followed by perpendiculardisplacement relative to one another. (See FIG. 11B.) The dimensions ofsubstrates 2,3 may also be such that, for example, substrate 2 may havea greater width and/or length than substrate 3. Thus, simply bypositioning substrates 2,3 in spaced-apart relationship and so thattheir central portions are aligned will allow for peripheral edges ofthe substrate with greater dimensions to extend beyond the peripheraledges of the substrate with smaller dimensions. Thus, a portion ofconductive electrode coating 4 or 4′ will be exposed, depending onwhichever of substrates 2,3 is dimensioned with a larger width and/orlength. (See FIG. 11C.)

[0159] An exposed portion of the conductive electrode coatings 4,4′ mayalso be provided in a flush design, where the substrates 2,3 are sizedand shaped to like dimensions. In such a flush design, the firstsubstrate 2 and the second substrate 3 may each be notched atappropriate positions along their respective edges. The notches soprovided present convenient areas for bus bars and/or point contacts towhich are connected or affixed electrical leads 10 for the introductionof an applied potential thereto.

[0160] It may also be desirable to apply a layer of reflective materialonto the inward surface of substrate 3, and with substrate 3 notched inat least one appropriate position along its edges. In this way, directaccess is available to the conductive electrode coated inward surface ofsubstrate 2. Likewise, substrate 2 may be notched at a positionappropriately spaced from the notch or notches on substrate 3 to provideaccess to the conductive electrode coated inward surface of substrate 3.These notches provide convenient areas for electrical leads 10 to beconnected or affixed, and allow for such connection or affixation to bemade within the overall dimensions of the mirror assembly. For example,one or both of the substrates 2,3 may be notched along one or moreedges, and bus bars 9 may then be affixed over the exposed portion ofconductive electrode coatings 4,4′ of substrates 2,3. Electrical leads10 may then be joined to the bus bars 9. The electrical connection maybe made to the inward surfaces of substrates 2,3 without requiringfurther electrical connection on the peripheral edge of the mirrorassembly. As such, the electrical connection to conductive electrodecoatings 4,4′ will be hidden from view by the reflective element and/orthe mirror case or housing.

[0161] Alternatively, one or more localized lobe(s) may be provided atappropriate positions along the respective edges of substrates 2,3 tofacilitate direct access to the conductive coated inward surfaces ofsubstrates 2,3.

[0162] The bus bars 9 may also comprise thin metal films, preferablywith a thickness within the range of about 500 Å to about 50,000 Å orgreater. These thin metal film bus bars may be deposited onto conductiveelectrode 4 and/or 4′ by vacuum deposition, such as by evaporation orsputtering, and typically have a width within the range of about 0.05 mmto about 6 mm (and preferably with a thickness in the range of 0.05 μmto about 5 μm or greater) and are inboard from the perimeter edge of thesubstrate.

[0163] To form the thin metal film bus bars, a mask may be affixed overthe central region of the substantially transparent conductive electrodecoated substrate leaving at least a portion, and preferably most, of theperimeter region unmasked. Then a thin film of metal, such as chromiumand/or silver, or other metals such as copper, titanium, steel,nickel-based alloys, and the like, may be deposited using a vacuumdeposition process across the entire surface, coating both the maskedcentral region and the unmasked perimetal region. Thereafter, the maskmay be removed leaving the central region of the substrate transparentand with a conducting thin metal film bus bar deposited on at least aportion of the perimetal region. For manufacturing economy, it may bedesirable to establish thin metal film bus bars on the inward surface ofsubstrate 2, conductive electrode coating 4′ and electrochromic solidfilm 7 in a unitary vacuum deposition process step. Thus, it may beconvenient to overlay in central alignment, for example, substrate 3(being uncoated glass) onto the substantially transparent conductiveelectrode coated surface of substrate 2, where substrate 3 is sized andshaped about 2 mm to about 4 mm smaller in both length and width thansubstrate 2 (see e.g., FIG. 11C). A peripheral edge of substrate 2 ofabout 2 mm to about 4 mm will then extend beyond the peripheral edge ofsubstrate 3. In this instance, substrate 2 is made, for example, fromITO-coated glass, and substrate 3 is made from clear soda-lime glass.With this configuration, a vacuum deposition process may be used todeposit a thin metal film and, optionally, a metal oxide thereover,across the entire surface.

[0164] Upon completion of the deposition process, the substrates 2,3 maybe separated from one another. The formation of a thin metal film busbar consisting of a chromium/silver coating about the peripheral edge ofsubstrate 2 may then be seen where, because of its smaller dimensions,substrate 3 has served the role of a mask to the major, central regionof substrate 2 during deposition. That is, when substrate 3 is removed,the major, central region of substrate 2 has not been coated during thedeposition and the transparency of the major, central region ofsubstrate 2 is maintained. Because this thin metal film bus bar ishighly conductive and extends about the entire periphery of substrate 2,electric potential may be supplied by means of a point electricalcontact (optionally with local removal of any metal oxide) without theneed for a large metal clip or ribbon connector wire as has beenconventionally used heretofore. Moreover, because the thin metal filmbus bar consists of a chromium/silver coating it forms a highlyreflective perimeter coating which may be used to conceal any sealand/or electrical connection for the electrochromic cell. [See U.S. Pat.No. 5,060,112 (Lynam), the disclosure of which is hereby incorporatedherein by reference.]

[0165] In addition, the surface of substrate 3 which was exposed duringdeposition is now coated with a chromium/silver/tungsten oxide stack,which may be used as the inward surface in forming an electrochromiccell. The cut edge of substrate 3 is also coated with a chromium/silvercoating during the unitary vacuum deposition process due to theinevitable overspray which occurs in such a process. Thischromium/silver coating around the cut edge of substrate 3 may itselfconveniently be used to establish an electrical connection to applypotential to electrochromic solid film 7.

[0166] The applied potential may be supplied from a variety of sourcesincluding, but not limited to, any source of alternating current (AC) ordirect current (DC) known in the art, provided that, if an AC source ischosen, control elements, such as diodes, should be placed between thesource and the conductive electrode coatings 4,4′ to ensure that thepotential difference between the conductive electrode coatings 4,4′ doesnot change with variations in polarity of the applied potential from thesource. Suitable DC sources include storage batteries, solar thermalcells, photovoltaic cells or photoelectrochemical cells.

[0167] The applied potential generated from any of these sources may beintroduced to the electrochromic element 1 within the range of about0.001 volts to about 5.0 volts. Typically, however, an applied potentialof about 0.2 volts to about 2.0 volts is preferred to cause theelectrochromic element to dim to a colored state—i.e., to change theamount of light transmitted therethrough. For electrochromic solid filmslike tungsten oxide, the negative polarity of the potential should beapplied onto whichever of substrates 2,3 the electrochromic solid film 7is deposited.

[0168] Also, in constructions where a metal conductor layer or a metalconductor/reflector layer is contacted with an electrochemically activemedium (such as an electrolyte prepared in accordance with thisinvention or an electrochemichromic solution like those disclosed in,for instance, Byker I and Varaprasad I), it is preferable to apply acathodic potential (i.e., a negative applied potential) to the metallayer to achieve coloration of the electrochromic device (e.g., anelectrochromic rearview mirror). In order to bleach such electrochromicdevices, it is preferable to apply a potential of zero volts to themetal conductor layer.

[0169] The teaching of the present invention is well-suited for use inelectrochromic mirrors whose functional surface is substantially planaror flat. For example, flat electrochromic mirrors for motor vehicles maybe manufactured with the electrochromic element of the presentinvention.

[0170] In addition, the present teaching is well-suited for use inelectrochromic mirrors having a curved functional surface, with a convexcurvature, a compound curvature, a multi-radius curvature, asphericalcurvature, an aspheric curvature, or combinations of such curvature.(See FIG. 13.) Convex electrochromic mirrors for motor vehicles may bemanufactured with the electrochromic element of the present invention,with radii of curvature typically within the range of about 25″ to about250″, preferably within the range of about 35″ to about 120″, as areconventionally known.

[0171] Multi-radius mirrors for motor vehicles, such as those describedin U.S. Pat. No. 4,449,786 (McCord), may also be manufactured inaccordance with the present invention. Multi-radius mirrors for motorvehicles may typically be used on the driver-side exterior of a motorvehicle to extend the driver's field of view and to enable the driver tosee safely and to avoid blind-spots in the rearward field of view.Generally, such mirrors have a region of a higher radius (i.e.,substantially planar or flat) closer or inboard to the driver thatserves principally as the primary driver's rear vision function and aregion of a lower radius (i.e., more curved) farther or outboard fromthe driver that serves principally as the blind-spot detection zone inthe mirror.

[0172] In forming spherical mirrors, such as convex exterior mirrors, oraspherical mirrors such as the multi-radius mirror 44 in FIG. 13, theradius of curvature for the substrates to be used for the laminateassembly formed by the electrochromic element 1 between substrates 2,3should be matched. Moreover, in aspherical mirrors, the two substrates2,3 in the laminate assembly should be matched so that the local radiusin one substrate, for example in the first substrate 2, is located over,and oriented to align with, its corresponding local radius in the othersubstrate, for example, in the second substrate 3. (See FIG. 13.)

[0173] To achieve such radius of curvature matching, a desired shape forthe substrates of the aspherical mirrors may be cut from a flatsubstrate of dimensions greater than that of the desired multi-radiusshape. This initial flat substrate (“a flat minilite”) may have arectangular, square or circular shape, or may be of the general shape ofthe desired multi-radius shape, or any other convenient alternativeshape. Glass lites from which the flat minilites may be cut aredesirably substantially colorless or tinted soda-lime sheets of glass.In addition, depending on the particular mirror construction and whetherthe desired bent shape derived from the flat minilite is to be employedas the front substrate 2 or the rear substrate 3, glass lites/flatminilites, from which the desired bent shape may be derived, may becoated with a substantially transparent conductive electrode coating,such as ITO or fluorine-doped tin oxide. As noted supra, fluorine-dopedtin oxide coated glass is commercially available from Libbey-Owens-FordCo. under the “TEC-Glass” tradename.

[0174] Once cut, the oversized flat minilites may be bent to the desiredmulti-radius using either conventional slump bending or press bending.Also, individual minilites may be bent to compound curvature or two flatminilites may be bent together as a matched pair. To manufacture amatched pair of bent minilites, two flat minilites may be stacked on topof one another, loaded in a tandem orientation into a bending press andbent together to the desired curvature (which may be spherical oraspherical) in one bending process step.

[0175] Where individual bent minilites are to be manufactured, any onebent minilite manufactured in any one bending process step is intendedto match any other bent minilite. In electrochromic mirrors, it may beadvantageous to use the twin bent minilites manufactured in tandem oneon top of the other in the one bending operation step as a given matchedpair to assemble a laminate construction.

[0176] The desired substrates may be cut from bent minilites to thedimension and shape suitable for use in the intended laminateconstruction of the particular electrochromic mirror. To the extent thatthe cullet trimmed away from the bent minilite manufactured as describedsupra conforms least to the intended radius design, bending oversizedminilites is recommended. However, and particularly where the bendingoperation is to be attentively supervised, the desired dimensioned shapemay first be cut from flat glass lites, with the desired dimensionedshape then bent to the desired multi-radius curvature.

[0177] It may be advantageous to cut multi-radius front and rearsubstrates from their respective bent minilites to facilitate properalignment of a local radius on the first substrate relative to itscorresponding local radius on the second substrate. In this regard, amatched pair of bent minilites may be assembled into a laminateconstruction with the first substrate laterally displaced from thesecond substrate, yet sustaining local to local radius alignment therebetween. In addition, should there be an asymmetry in radius, oneperimeter length, LC, of the bent minilite may be identified as thelower radius (more curved) part of the minilite compared with itsopposite perimeter length, LF, identified as the higher radius (moreflat) part of that same bent minilite. Likewise, for its twin match in amatched pair of bent minilites, there may exist corresponding LC′ andLF′ perimeter lengths.

[0178] Suitable jigs or the like may be used to assemble a laminateconstruction of an electrochromic mirror with their correspondingperimeter lengths aligned. For example, LC may be aligned a fewmillimeters (e.g., 3 mm) inboard relative to LC′ so that their localradii are mutually aligned and the desired electrical connection isestablished along LC′ and LF. This may be accomplished by cutting ameasured portion (e.g., 3 mm) of bent glass away from along LC and LF′and using jigs to align the now-cut edge of LC to the same measureddistance (e.g., 3 mm) inboard from LC′, with the respective substratesjuxtaposed. Because of this alignment, local radius conformity betweenthe substrates in a laminate construction may be established.

[0179] Alternatively, the bent minilites may be cut from oversizedminilites so that one cut substrate may be laid on top of another cutsubstrate aligned in substantially flush relationship so that local tolocal radius conformity may be maintained and electrical connection maybe established [see Lynam IV, the disclosure of which is herebyincorporated herein by reference].

[0180] While not required, the minilites may be sufficiently oversizedto allow more than one substrate to be cut out from a given minilite, ifthe bending tool is appropriately designed. By so doing, the substratecutting process benefits from economies of scale. For example, twosubstrates may be cut from the one sufficiently oversized bent minilite.These side-by-side matched twin substrates may be used as substrates 2,3to construct the same electrochromic laminate assembly, or they may beused to serve as a substrate in any electrochromic laminate assembly.

[0181] Also, certain substantially transparent conductive electrodecoatings, such as doped tin oxides, are aerobically inert, and as suchmay be bent in an ordinary air atmosphere without taking precautions toexclude oxygen. However, suitable precautions should be taken to avoidany crazing, hazing or optical deterioration of the conductive electrodecoatings 4,4′ during the bending process. Other substantiallytransparent conductive electrode coatings, such as ITO, may be bent fromflat sheet stock using techniques such as those described in U.S. Pat.No. 4,490,227 (Bitter), the disclosure of which is hereby incorporatedherein by reference. After or during heat treatment of ITO, such as in abending/annealing process which produces spherical and aspherical shapedsubstrates suitable for assembling laminate constructions forelectrochromic mirrors or when firing ceramic frit bus bar material suchas silver conductive frit #7713 (Du Pont), it may be desirable toestablish a reducing atmosphere, as described in Bitter, such as ahydrogen-rich atmosphere, like that established with forming gas.

[0182] Glass lites and minilites may also be manufactured into sphericaland/or aspherical shaped substrates without first being coated with aconductive electrode. In such instances, after the spherical and/oraspherical bent minilites or shaped substrates are manufactured, aconductive electrode coating, such as ITO, may thereafter be depositedonto the concave surface of the substrate 2 and the convex surface ofthe substrate 3.

[0183] A demarcation means 22 may be used in the multi-radius mirrors asdescribed herein to separate the more curved, outboard region 55 (i.e.,that portion of an exterior driver-side multi-radius mirror outboard andfarthest from the driver) used by the driver principally as theblind-spot detection zone from the less curved, more flat inboard region65 (i.e., closer to the driver) used by the driver principally for theprimary rear vision function. (See FIG. 13.)

[0184] The demarcation means 22 may be a black or darkly coloredcontinuous line or closely interspaced dots, dashes or spots(silk-screened or otherwise applied), which divides the outboard regionfrom the inboard region of the multi-radius mirror. This black or darklycolored dividing line (or its aforestated equivalent) may assist thedriver of a motor vehicle to discern the difference between images inthe outermost, more curved region from those in the innermost, more flatregion of the mirror. The thickness of this dividing line should bewithin the range of about 0.1 mm to about 3 mm, with about 0.5 mm toabout 2 mm being preferred.

[0185] The demarcation means 22 may be constructed from an organicmaterial, such as a polymer like an epoxy; an inorganic material, suchas a ceramic frit; or a mixed organic/inorganic material. Suchdemarcation means 22 may be constructed to include, for example, anepoxy coupled with glass spacer beads, or plastic tape or a die cut fromplastic tape. The demarcation means may be placed onto the conductiveelectrode coatings 4,4′ of either or both of substrates 2,3 bysilk-screening or other suitable technique prior to assembling thedevice. Also, the demarcation means 22 may be applied to any or all ofthe surfaces of substrates 2,3—i.e., the inward surfaces of substrates2,3 or the opposite, non-inward surfaces of substrates 2,3. Additivesmay be included in the material used as a demarcation means to provideor enhance color, such as a dark color, like black, or dark blue or darkbrown; to enhance stability (e.g., ultraviolet stabilizing agents suchas described herein); or to increase adhesion (e.g., coupling agents,such as silane-, titanium-, or zirconium-based coupling agents).Alternatively, a dividing line may be established by etching a surfaceof substrate 2 and/or 3 (such as by sand blasting, laser etching orchemical etching) with optional staining of the etched-surface todevelop a dark colored dividing line.

[0186] Where ceramic frits are used as a demarcation means and/or wherebus bars are formed by applying a silver conductive frit [e.g., #7713(Du Pont)] around the periphery and inboard from the edge of the inwardsurface(s) of substrate 2 and/or substrate 3, it may be convenient tosilk-screen or otherwise apply the material to either or both of thesubstrates 2,3 prior to bending. In this way, the bending operationserves the dual purpose of bending and firing/curing the ceramic fritonto the substrates. In addition, where epoxies or other organic-basedmaterials are used as the demarcation means and/or materials which actas bus bars, it may be convenient to silk-screen or otherwise apply thematerial to either or both of the substrates prior to final cure of thematerial used as the sealing means so that the sealing means, thedemarcation means and/or material which acts as bus bars may befired/cured in one and the same operation step. A dividing line may alsobe established within the cavity formed between substrates 2,3.

[0187] A driver textural warning 23, such as the conventional texturalwarning “objects in mirror are closer than they appear”, may be includedin the outermost more curved portion 55 of an electrochromicmulti-radius exterior mirror according to this invention. (See FIG. 13.)Alternatively, a driver textural warning may be included in theinnermost less curved region 65. Heretofore, such warnings have beenestablished through sandblasting or as described in O'Farrell.Alternatively, textural warnings may be applied by silkscreening onto asurface of one of the substrates 2,3 of the mirror assembly or by othersuitable techniques, such as laser etching, onto the reflective elementof the mirror which is coated onto a surface of substrate 3.

[0188] On demand displays 14 may be positioned behind the reflectiveelement of the mirror (see FIGS. 9 and 10) and become activated by userinput or by input from a sensor, such as a supplementary vision device(e.g., camera, sensor, proximity detector, blind-spot detector, infraredand microwave detector), temperature sensor, fuel sensor, faultdetector, compass sensor, global positioning satellite detector, hazarddetector or the like. In addition, a vehicle function (such as a turnsignal, hand brake, foot brake, high beam selection, gear change, memoryfeature selection and the like) may activate the on demand display. Theon demand display may also be activated by a function such as a compass,clock, a message center, a speedometer, an engine revolution per unitmeter and the like. In the context of their use in conjunction withrearview mirrors for motor vehicles, an on demand display, when notactive or activated, should desirably remain at least substantiallyunobservable or undetectable by the driver and/or passengers. Similarly,in other applications with which these on demand displays may bedesirably used, they should remain at least substantially unobservableor undetectable when not activated.

[0189] On demand displays 14 should be an emitting electronic display,such as a vacuum fluorescent display, a light emitting diode, a gasdischarge display, a plasma display, a cathode ray tube, anelectroluminescent display and the like.

[0190] Conventionally, the reflective element in electrochromic mirrorsis constructed by coating the rearmost (non-inward) surface of thesecond substrate 3, with a reflective element using a wet chemicalsilver line mirror coating. This rearmost surface is typically coatedwith a layer of silver 8, and then protected with a thin film layer ofcopper 19 which itself is overcoated with a protective material 20,typically a paint such as a lead-based paint. In this construction, thelight transmissivity through the mirror is substantially opaque—i.e.,substantially less than about 0.01%. To place a display, camera, sensoror the like behind such a conventional mirror, a “window” 13 throughwhich light may pass must be created as described hereinafter.

[0191] With reference to FIGS. 8, 9 and 10, it may be seen that ondemand display capability may be introduced to a mirror through thewindow 13 that has been previously created therein [typically, by sandblasting, mechanical erosion (e.g., with a spinning rubber), laseretching, chemical etching and the like] by coating a layer of reflectivematerial, such as a thin film of a metal 16 (e.g., a medium reflector,such as chromium, titanium, stainless steel and the like, having athickness preferably less than about 750 Å), onto the rearmost(non-inward) surface of substrate 3 at the portion of the substratewhere the window 13 exists. (See FIG. 10.) It may be preferable to use amedium reflector, such as chromium, titanium, stainless steel and thelike, because such medium reflectors are durable, scratch resistant andresistant to environmental degradation without the need for additionalovercoat layers like paints, lacquers, or other oxide coatings.Nevertheless, such overcoat layers may, of course, be used. Also, a highreflector such as silver or aluminum may be used, if desired. The window13, now being only partially opaque in light transmissivity, issubstantially light reflecting.

[0192] This partially transmitting/substantially reflecting window maybe established through evaporating or sputtering (using vacuumdeposition techniques) chromium metal over the window to a thickness ofup to about 750 Å. By so doing, light transmittance within the range ofabout 1% to about 10% may be achieved, while also achieving lightreflectance within the range of about 40% to about 65%. This method,however, introduces increased manufacturing costs (e.g., by firstcreating the window in the silver line-coated rearmost surface ofsubstrate 3 and then vacuum depositing thereover the thin film ofchromium). Also, the differences in reflectivity between the higherreflectance off the silver reflective element and the lower reflectanceoff the partially transmitting, lesser reflecting window may bedetectable by or noticeable to an observer.

[0193] An alternative method involves the use of a partiallytransmitting (i.e., light transmission within the range of at leastabout 1% to about 20%), substantially reflecting (i.e., lightreflectance within the range of least about 40% to greater than about70%) metal foil or reflector-coated polymer sheet or film 15, such asmetalized polymer sheet or film, like aluminum or chromium coatedacrylic sheet or polyester “MYLAR” film (commercially available from DuPont). Such a foil, or sheet or film 15, reflector coated with a thinfilm of metal 16 may be contacted with, or adhered to using an opticaladhesive 18, preferably an index matching adhesive such as describedhereinafter, the window 13 in the layer of reflective material onsubstrate 3.

[0194] Likewise, an appropriately sized glass cover sheet 15 (or apolymer cover sheet) which is coated with a thin film of metal 16 thatis partially light transmitting (preferably, about 1% to about 20%), andyet substantially light reflecting (preferably, at least about 40% togreater than about 70%) may be contacted with, or adhered to using anoptical adhesive 18 as described herein, the window 13 in the layer ofreflective material on substrate 3. (See FIG. 9.) The glass cover sheet15 may be any desired shape and should be sufficiently large to at leastcover the entire window 13 created in the silver-coated, rearmostsurface of substrate 3 (which may be suitable to accommodate, forexample, compass displays, like the compass displays described inO'Farrell and Larson).

[0195] It may be convenient to coat glass lites with a high reflector,such as a thin film coating of aluminum or silver, to a thickness thatachieves the desired partial light transmittance and substantial lightreflectance. Alternatively, a medium reflector, such as a thin filmcoating of chromium, stainless steel, titanium or the like, may be usedto coat the glass lites.

[0196] An inorganic oxide coating, such as silicon dioxide, titaniumdioxide, zinc oxide or the like, may also be overcoated onto the thinfilm metal reflector coating to impart resilience, resistance againstenvironmental degradation, enhance scratch resistance and enhanceoptical performance. Likewise, a thin film of magnesium fluoride, or acombination of thin films of dielectric materials such as describedsupra, may be used to overcoat the thin film metal reflector coating. Aclear coat of a lacquer, such as an acrylic- or a urethane-based lacqueror the like, is still another choice which may be used to overcoat thethin film metal reflector coating.

[0197] Once formed, the partially transmitting/substantially reflectingglass lites may be subdivided into a multitude of smaller sized coversheets to cover the window in the reflector on the rearmost (non-inward)surface of substrate 3. More specifically, a square, circle or rectanglemay be cut to dimensions of about 1 to about 6 mm or larger than thedimensions of the window for the display. The square- orrectangular-shaped glass cover sheets may then be contacted with, oradhered to, the rearmost (non-inward) surface of substrate 3 to coverthe previously established window for the display.

[0198] An optical adhesive 18 that is index matched to the refractiveindex of glass (i.e., about 1.52) may be used to adhere the glass coversheet 15 to the rearmost (non-inward) surface of substrate 3. Suchoptical adhesives maximize optical quality and optical index matching,and minimize interfacial reflection, and include plasticized polyvinylbutyral, various silicones, polyurethanes such as “NORLAND NOA 65” and“NORLAND NOA 68”, and acrylics such as “DYMAX LIGHT-WELD 478”. The glasscover sheet 15 may be positioned with its semitransparent metalreflector coating 16 closest to the rearmost (non-inward) surface ofsubstrate 3 so that the mirror construction comprises an assembled stackof the glass cover sheet 15/semitransparent reflector metal coating16/optical adhesive 18/rearmost (non-inward) surface of substrate 3. Inthis construction, the optical adhesive is used as both an adhesive andas a protectant for the semitransparent metal reflector-coating 16 ofthe glass cover sheet 15. Such a use of semitransparent reflector-coatedglass cover sheets 15/16 lends itself to economical and automatedassembly. Also, the cover sheet may be made from glass that is coatedwith a dichroic mirror or made from polymer reflector material (“PRM”),as described hereinafter.

[0199] As an alternative to localized reflector coating with a thinmetal film as shown in FIG. 10, or localized use of cover sheets, foils,films, and the like as shown in FIG. 9, at the non-inward surface ofsubstrate 3 at window 13, similar localized reflector means can beemployed at the inward facing surface of substrate 3 at the location ofwindow 13.

[0200] An emitting display 14 may also be positioned behind the rearmost(non-inward) surface of the glass cover sheet 15 (which itself ispositioned behind substrate 3 of the electrochromic mirror assembly). Inthis regard, it may be desirable to use a thin glass for the cover sheet15 to minimize multiple imaging and/or double imaging. The thickness ofthe cover sheet need not be thicker than about 0.063″, with suitablethicknesses being about 0.063″; about 0.043″; about 0.028″; about 0.016″and about 0.008″. However, if desired the thickness of the cover sheet15 may be greater than about 0.063″.

[0201] Again with reference to FIG. 5, where the layer of reflectivematerial is coated onto the inward surface of substrate 3, improvedoptical performance may be observed without reducing the thickness ofsubstrate 3. In such constructions, a relatively thick glass (having athickness of greater than about 0.063″) may be used for substrate 3 witha thin glass (having a thickness of about 0.063″ or less) used forsubstrate 2 while maintaining good mechanical properties due to therelatively greater stiffness of substrate 3. Improved opticalperformance may also be observed due to the relative closeness of thelayer of reflective material (coated onto the inward surface ofsubstrate 3) and the frontmost (non-inward) surface of substrate 2.

[0202] An illustration of this aspect of the present invention may beseen where substrate 3 is fabricated from “TEC 10” glass (having a sheetresistance of about 10 ohms per square), with a thickness of about 3 mm,and substrate 2 is fabricated from soda-lime glass (coated with HW-ITOhaving a sheet resistance of about 12 ohms per square as a substantiallytransparent conductive electrode coating 4), with a thickness of about0.043″. In this construction, the fluorine-doped tin oxide surface ofthe substrate 3 fabricated from “TEC 10” glass is positioned inward (andovercoated with a metal reflector/conductive electrode coating 4′) andthe HW-ITO coated surface of substrate 2 is also positioned inward sothat the coated substrates 2,3 face one another.

[0203] A silicon or similar elemental semiconductor material may also beused as a reflective element 8 coated onto either the rearmost(non-inward) surface or the inward surface of substrate 3. Methods formaking elemental semiconductor mirrors for motor vehicles are taught byand described in commonly assigned co-pending U.S. patent applicationSer. No. 07/700,760, filed May 15, 1991 (“the '760 application”), thedisclosure of which is hereby incorporated herein by reference. Where itis desired that the high reflectance off the elemental semiconductorreflector be within the range of at least about 60% to greater thanabout 70%, an undercoat of a thin film layer of silicon dioxide betweena thin film layer of silicon and the surface of the substrate onto whichit is coated may be used to enhance reflectivity performance [see e.g.,the '760 application, and U.S. Pat. No. 4,377,613 (Gordon) and U.S. Pat.No. 4,419,386 (Gordon), the disclosures of each of which are herebyincorporated herein by reference].

[0204] In addition, the layer of silicon and/or an undercoat of silicondioxide may be deposited using techniques such as vacuum deposition,spray deposition, CVD, pyrolysis and the like. For example, in-linedeposition on a float glass line, and preferably in-bath, in-linedeposition on a float glass line (as known in the glass manufacturingart) using CVD may be employed to deposit silicon layers andsilicon/silicon dioxide thin film stacks onto float glass to provide areflector for substrate 3 that is both highly reflecting and partiallytransmitting. A further advantage of these elemental semiconductorcoatings is that they are bendable.

[0205] For example, a glass coated with a reflective element may beconstructed by depositing onto a glass substrate a first layer ofelemental silicon at an optical thickness of about 6,950 Å, followed bydeposition of a second layer of silicon dioxide at an optical thicknessof about 1,050 Å, which in turn is followed by deposition of a thirdlayer of elemental silicon at an optical thickness of about 1,600 Å.Such a construction has a luminous reflectance of about 69% beforeheating and bending; and a luminous reflectance of about 74% afterheating and bending. A substantially transparent conductive electrodecoating, such as doped tin oxide (e.g., fluorine-doped tin oxide) andthe like, may be coated over the third layer of elemental silicon toconstruct a highly reflecting, electrically conducting glass substratesuitable for use in electrochromic mirrors and electrochromic deviceswhere the coated substrate may be bent without unacceptabledeterioration in its optical and electrical properties. Preferably,reflector-coated substrates constructed using multi-layer stacks, suchas a glass/silicon/silicon dioxide/silicon stack (with or withoutadditional undercoating or overcoating stack layers), may be depositedin-bath, on-line onto glass being manufactured on a float glass line.

[0206] It may also be advantageous to employ bendable reflector-coatedsubstrates and techniques for manufacturing the same as taught by anddescribed in the '760 application, and multi-layer stacks, such as theglass/silicon/silicon dioxide/silicon stack as described supra, with orwithout an additional overcoating of a substantially transparentconductive electrode coating such as fluorine-doped tin oxide and thelike. Bendable coatings may be advantageous in minimizing manufacturingrequirements since depositing a thin film of metal generally requiresthe steps of first bending the non-reflector coated substrate and thencoating the bent substrate with the layer of reflective material.

[0207] As described supra, it may be advantageous to constructelectrochromic mirrors whose reflective element 8 is located within thelaminate assembly. This may be achieved by coating the inward surface ofsubstrate 3 with a layer of reflective material 8, such as silver, sothat the silver coating (along with any adhesion promoter layers 11) isprotected from the outside environment. For example, a layer ofreflective material 8 may be vacuum deposited onto the inward surface ofsubstrate 3 in one and the same process step as the subsequentdeposition of the electrochromic solid film 7 onto substrate 3. Thisconstruction and process for producing the same not only becomes moreeconomical from a manufacturing standpoint, but also achieves highoptical performance since uniformity of reflectance across the entiresurface area of the mirror is enhanced. The thin film stack [whichcomprises the electrochromic solid film 7 (e.g., tungsten oxide), thelayer of reflective material 8 (e.g., silver or aluminum) and anyundercoat layers between the layer of reflective material 8 andsubstrate 3] should have a light reflectance within the range of atleast about 70% to greater than about 80%, with a light transmissionwithin the range of about 1% to about 20%. Preferably, the lighttransmission is within the range of about 3% to about 20%, and morepreferably within the range of about 4% to about 8%, with a lightreflectance greater than about 80%.

[0208] The inward facing surface of substrate 3 may be coated with amulti-layer partially transmitting/substantially reflecting conductorcomprising a partially transmitting (preferably, in the range of about1% to about 20%)/substantially reflecting (preferably, greater thanabout 70% reflectance, and more preferably, greater than about 80%reflectance) metal layer (preferably, a silver or aluminum coating) thatis overcoated with an at least partially conducting transparentconductor metal oxide layer [comprising a doped or undoped tin oxidelayer, a doped or undoped indium oxide layer (such as indium tin oxide)or the like]. Optionally, an undercoating metal oxide (or another atleast partially transmitting metal compound layer, such as a metalnitride like titanium nitride) may be included in the stack whichcomprises the multi-layer conductor. This multi-layer conductorfunctions as reflective element 8, and can be overcoated withelectrochromic solid film 7 during fabrication of an electrochromicmirror incorporating on demand displays. Alternatively, the multi-layerconductor described supra may be used on the inward surface of substrate3, with the electrochromic solid film 7 coated onto the inward surfaceof substrate 2.

[0209] A light reflectance of at least 70% (preferably, at least 80%)for the reflective element to be used in an electrochromic mirrorincorporating on demand displays is desirable so that the bleached(unpowered) reflectivity of the electrochromic mirror can be at least55% (preferably, at least 65%) as measured using SAE J964a, which is therecommended procedure for measuring reflectivity of rearview mirrors forautomobiles. Likewise, a transmission through the reflective element of,preferably, between about 1% to 20% transmission, but not much more thanabout 30% transmission (measured using Illuminant A, a photopicdetector, and at near normal incidence) is desirable so that emittingdisplays disposed behind the reflective element of the electrochromicmirror are adequately visible when powered, even by day but, whenunpowered and not emitting, the displays (along with any othercomponents, circuitry, backing members, case structures, wiring and thelike) are not substantially distinguishable or visible to the driver andvehicle occupants.

[0210] With reference to FIGS. 9 and 10, emitting displays 14, such asvacuum fluorescent displays, light emitting diodes, gas dischargedisplays, plasma displays, cathode ray tubes, electroluminescentdisplays and the like may also be placed in contact with, or adhered tousing an adhesive 17, 18 such as an epoxy, the rear of substrate 3.Generally, such emitting displays may only be observable when powered soas to emit light.

[0211] A variety of emitting displays 14 may be used in this connectionincluding, but not limited to, double heterojunction AlGaAs very highintensity red LED lamps, such as those solid state light emittingdisplay LED lamps which use double heterojunction Al/GaAs/GaAs materialtechnology [commercially available from Hewlett Packard Corporation,Palo Alto, Calif. under the designation “T-1¾ (5 mm) HLMP-4100-4101”].

[0212] Alternatively, vacuum fluorescent displays, such as 12V batterydriven high luminance color vacuum fluorescent displays may beadvantageously used [commercially available from Futaba Corporation ofAmerica, Schaumburg, Ill. under the designations S-2425G, S-24-24G,S-2396G and S2397G]. It may also be advantageous to use displays 14 thatoperate efficiently at about 12V or lower since these voltages areparticularly amenable to motor vehicles. Also, ultrahigh luminancevacuum fluorescent displays, suitable for heads-up-display applicationsin motor vehicles may be used with appropriate circuitry, such as Type3-LT-10GX [commercially available from Futaba Corporation]. Suitablevacuum fluorescent displays are also commercially available from NECElectronics Incorporated, Mountain View, Calif., such as under thedesignation Part No. FIP2QM8S.

[0213] It may also be desirable, particularly where the reflectiveelement is at least partially light transmitting, to use a lightabsorbing means, such as a black-, brown- or blue-colored or othersuitably colored absorbing coating, tape, paint, lacquer and the like,on portions of the rearmost (non-inward) surface of substrate 3 wheredisplays are not mounted. It may be desirable to use substantiallyopaque, and preferably dark colored tape or plastic film and the like,across the surface of substrate 3, such as by adhering to protectivematerial 20, preferably across substantially the entire rear surface,except where any displays are to be positioned. By so doing, anysecondary images or aesthetically non-appealing mirror case illuminationdue to stray light emittance from the display may be reduced.

[0214] Placement of apertures or cutouts in a tape or film backing mayexpedite the assembly of such mirrors by guiding the assembler to thepoint where the desired display or displays is to be mounted. The tapeor film backing may also serve as an anti-scatter means to enhancesafety and prevent injury by retaining any glass shards which may resultdue to mirror breakage, for example caused by impact from an accident.

[0215] Suitably colored paints, inks, plastic films or the like may beapplied to the surface of substrate 3 where the display 14 is to beplaced to change or effect the color of the display. Also, the display14 may be adhered to a surface of the substrate using an adhesive 18,such as an index matching adhesive 17, 18, that may be dyed to effectcolor and/or contrast enhancement in the display [see e.g., Larson, thedisclosure of which is hereby incorporated herein by reference].

[0216] Generally, and particularly when the electrochromic element is inits bleached, uncolored state, it may be desirable for the image of thedisplay—e.g., an information display, such as a compass display, a clockdisplay, a hazard warning display or the like—to have a luminance withinthe range of at least about 30 foot lamberts to about 80 foot lamberts(preferably, within the range of at least about 40 foot lamberts toabout 60 foot lamberts), as measured with the display placed behind, andemitting through, the electrochromic mirror and with the electrochromicelement in its fully transmitting, bleached state. With this level ofluminance, such a display may be read easily even with bright ambientlevels of light. Also, the electronic circuitry taught by and describedin Larson may be used to appropriately dim the display to suit nighttimedriving conditions and/or to compensate for any dimming of theelectrochromic element. Generally, at night the luminance of the displayis about 15-40%, preferably about 20-35%, that of the daytime value.

[0217] During daytime lighting conditions, drivers of motor vehiclesmounted with an electrochromic mirror (interior, exterior or both)benefit from relatively high reflectance (at least about 55%, with atleast about 65% typically being preferred) when in the bleached “day”state. Any display positioned behind the electrochromic mirror shouldhave a sufficiently high luminance to permit the display (which may bedigital, alpha-numeric, analog or combinations thereof) to emittherethrough and be readable. The display 14 should be readable evenwhen ambient conditions within the cabin of a motor vehicle (or outside,where electrochromic exterior rearview mirrors are used or where theelectrochromic interior rearview mirror is mounted in a convertible withits top down) are bright, such as midday on a sunny, cloudless day. Themirrors of the present invention may achieve a light reflectance of atleast about 55% for the high reflectance state where a high reflector inthe form of a thin film metal coating is used with a sufficientthickness to allow for light to transmit through the electrochromicelement 1, preferably within the range of about 1% to about 15%transmission, but not exceeding about 30% (as measured using IlluminantA and a photopic detector, with near normal incidence). Morespecifically, where silver is used as a high reflector, the mirrors ofthe present invention may achieve a light reflectance of at least about65% for the high reflectance state with a light transmissiontherethrough within the range of about 1% to about 20% transmission(measured as described supra). The thin film metal coating may have athickness within the range of about 200 Å to about 1,500 Å, preferablywithin the range of about 200 Å to about 750 Å.

[0218] It may also be desirable, particularly when used in conjunctionwith highly spectrally selective light emitting diodes and the like, touse PRM as a reflector placed between the display 14 and the rearmost(non-inward) surface of substrate 3. PRM is a spectrally selective,substantially reflecting (greater than about 50%) and significantlytransparent polymer reflector material [see T. Alfrey, Jr. et al.,“Physical Optics of Iridescent Multilayered Plastic Films”, Polym.Eng'g. & Sci., 9(6), 400-04 (1969); W. Schrenk et al., “CoextrudedElastomeric Optical Interference Film”, ANTEC '88, 1703-07 (1988); andsee generally U.S. Pat. No. 3,711,176 (Alfrey, Jr.); U.S. Pat. No.3,557,265 (Chisolm) and U.S. Pat. No. 3,565,985 (Schrenk). PRM iscommercially available from Dow Chemical Co., Midland, Mich., such asunder the designation PRM HU75218.03L, which is a 0.125″ thick sheetingmade of multiple polymer layers (e.g., 1305 layers), having differingrefractive indices and transparent/transparent CAP layers. This PRMexhibits a light reflectance of about 58% and a generally neutral lighttransmittance. Another PRM, designated as PRM HU75218.08L, also is a0.125″ thick sheeting, made from multiple polymer layers (e.g., 1305layers), with a light reflectance of about 58%. However, this PRM hastransparent/red CAP layers which results in a transmission which has adistinctly red tint. As such, it may be particularly well-suited for usein conjunction with the mirrors of the present invention that employ intheir construction red light emitting diodes, such as those typicallyemployed in hazard warning devices.

[0219] An array of light emitting diodes may be positioned behind awindow 13 in a mirror with an appropriately sized piece of PRMpositioned between the emitting displays 14 and the rearmost(non-inward) surface of the substrate 3. By choosing a PRM with aselective transmission which permits the passage of the bandwidth oflight emitted by the emitter but that substantially attenuates otherwavelengths not within that bandpass of light, optical efficiency may beenhanced. Indeed, PRM itself may be an appropriate reflective elementbehind which display emitters may be disposed. While PRM may bevulnerable to scratching and susceptible to degradation fromenvironmental exposure, substrates 2,3 offer desirable protection fromsuch damage. Use of PRM where the piece of PRM is larger than and coversthe window created in the reflective element on substrate 3 (but issmaller than the entire surface area of substrate 3) is particularlyattractive compared to the use of conventional dichroic mirrors [such asthin film dielectric stack dichroic mirrors (commercially available fromOptical Coatings Labs, Santa Rosa, Calif.)] as the reflective elementbecause of economic benefits.

[0220] Should it be desirable to use a PRM/emitting display, a substratewith or without a thin film of metal reflector coating that issubstantially transmitting may be positioned in front of the PRM.Suitable optical adhesives, preferably index matching adhesives asdescribed supra, may be used to construct a mirror that comprises alight emitting element which emits light through a sheet of PRM, whichis positioned behind a glass substrate through which the emitted lightalso passes. Such a mirror would appear reflective when the lightemitting element (e.g., a red LED such as described supra) is unpowered,yet would efficiently display a warning indicia when the light emittingelement is powered, strobed or flashed. Also, PRM being a polymermaterial is relatively easily formed by molding, slumping, bending andsimilar polymer forming methods, so conformance to a compound curvatureor convex curvature is facilitated.

[0221] In that aspect of the present invention directed to exteriorrearview mirrors for motor vehicles, it may be advantageous to use inconjunction therewith signal lights, security lights, flood lights,remote actuation and combinations thereof as taught by and described incommonly assigned co-pending U.S. patent application Ser. No.08/011,947, filed Feb. 1, 1993 (“the '947 application”), the disclosureof which is hereby incorporated herein by reference.

[0222] The electrochromic mirrors of the present invention may alsoinclude an anti-reflective means, such as an anti-reflective coating, onthe front (non-inward) surface of the outermost or frontmost substrateas viewed by an observer (see e.g., Lynam V); an anti-static means, suchas a conductive coating, particularly a substantially transparentconductive coating, such as ITO, tin oxide and the like; index matchingmeans to reduce internal and interfacial reflections, such as thin filmsof an appropriately selected optical path length; and/or light absorbingglass; such as glass tinted to a neutral density, such as “GRAYLITE”gray tinted glass (commercially available from Pittsburgh Plate GlassIndustries) and “SUNGLAS” gray tinted glass (commercially available fromFord Glass Co., Detroit, Mich.), which assists in augmenting contrastenhancement. Moreover, polymer interlayers, which may be tinted gray,such as those used in electrochromic devices as taught by and describedin Lynam I, may be incorporated into the electrochromic mirrorsdescribed herein.

[0223] The mirrors of this present invention, particularly rearviewmirrors intended for use on the exterior motor vehicles, may alsobenefit from an auxiliary heating means used in connection therewithsuch as those taught by and described in U.S. Pat. No. 5,151,824(O'Farrell) and U.S. patent application Ser. No. 07/971,676, filed Nov.4, 1992 (“the '676 application”), the disclosures of each of which arehereby incorporated herein by reference. Preferred among such heatingmeans are positive temperature coefficient (“PTC”) heater pads such asthose commercially available from ITW Chromomatic, Chicago, Ill. Theseheater pads employ conductive polymers, such as a crystalline organicpolymer or blend within which is dispersed a conductive filler likecarbon black, graphite, a metal and a metal oxide, [see e.g., U.S. Pat.No. 4,882,466 (Friel)]. The heater pads exhibit a positive temperaturecoefficient; that is, their resistance increases when the surroundingtemperature increases. Thus, the heater pads may be used as aself-regulating heating element.

[0224] As an alternative to a heater pad, a heater means, such as aresistance layer or heating film, may be deposited (such as throughvacuum deposition, thick film printing, screen printing, dispensing,contact printing, flow coating and the like) onto the outward facingsurface of substrate 3 (i.e., onto the rearmost surface of anelectrochromic mirror assembly). Suitable heater means include a PTCmaterial, a metal thin film layer (such, chromium, molybdenum, anickel-based alloy like Inconel and Hastelloy, stainless steel, titaniumand the like), and a transparent conductor thin film [such as tin oxide(doped or undoped) and indium tin oxide]. Such heater means aredisclosed in the '676 application.

[0225] The heater means referred to above function both to assure rapidcoloration and bleaching of an electrochromic rearview mirror whenoperated at low temperatures, and to remove any frost or dew which mayaccumulate on the outward facing surface of substrate 2 (i.e., theoutermost surface of the rearview mirror that is contacted by outdoorelements like rain, snow, dew and the like). For example, a convex ormulti-radius electrochromic outside mirror for an automobile may befabricated by forming substrate 3 through bending a fluorine-doped tinoxide coated glass substrate (such as a “TEC-Glass” product like “TEC20”, “TEC 12” or “TEC 10”) so that the transparent conductor doped tinoxide thin film coating is located on the concave surface of substrate3. The opposite, convex surface of substrate 3 is coated with a metalreflector layer (such as silver, optionally being undercoated with achromium adhesion promoter layer) and the reflector in turn is contactedwith an electrochromic layer, such as tungsten oxide. This convexsurface reflector coated/concave surface transparent conductor coatedsubstrate 3 is then mated with an equivalently bent substrate 2 that iscoated on its concave (inward facing) surface with a transparentconductor (such as fluorine doped tin oxide), and with an electrolytebetween the mated substrates to form an electrochromic exterior rearviewmirror. Next, bus bars (e.g., a conductive frit, solder or the like) areformed on opposing sides of the transparent conductor thin film heateron the rearmost, concave surface of substrate 3. When connected to the12 volt battery/ignition electrical supply of a vehicle, the transparentconductor thin film heater on the rearmost, concave surface of substrate3 heats the electrochromic medium and defrosts the front, outermost,concave surface of substrate 2.

[0226] If a display is to be mounted behind the reflective element, anappropriately sized and shaped aperture through the auxiliary heatingmeans should be used to accommodate the display but not leave portionsof the mirror unheated for de-icing or de-misting purposes. Likewise,should a heat distribution pad be used, such as an aluminum or copperfoil as described in the '676 application, an appropriately sized andshaped aperture should also be provided therein to accommodate suchdisplays. Where apertures are to be included in a PTC heater pad, apattern of resistive electrodes which contact the conductive polymer,which may typically be applied by a silk-screening process as describedin Friel, should be designed to accommodate the apertures in the pad. Inaddition, such a pattern may also be useful to thermally compensate forthe apertures in the pad. Alternatively, the resistiveelectrode/conductive polymer combination may be applied, for example,directly onto the rearmost (non-inward) surface of substrate 3, or ontoa heat distribution pad that is contacted and/or adhered thereto.

[0227] It may also be advantageous to provide mirrors in the form of amodule, which module comprises the mirror itself and its electricalconnection means (e.g., electrical leads); any heater pad (optionally,including a heat distribution pad) and associated electrical connectionmeans; bezel frames; retaining members (e.g., a one-piece plate) andelectrical connection means (see e.g., O'Farrell); actuators [e.g.,Model No. H16-49-8001 (right-hand mirror) and Model No. H16-49-8051(left-hand mirror), commercially available from Matsuyama, Kawoge City,Japan] or planetary-gear actuators [see e.g., U.S. Pat. No. 4,281,899(Oskamo) and the '947 application, the disclosures of each of which arehereby incorporated herein by reference] or memory actuators thatinclude memory control circuitry such as Small Electrical Actuator#966/001 which includes a 4 ear adjusting ring, 25 degree travel and anadd-on memory control and is available from Industrie Koot B.V. (IKU) ofMontfort, Netherlands; and brackets for mounting the module within thecasing or housing of a mirror assembly such as taught by and describedin the '947 application. Electrochromic mirrors may be assembled usingthese items to provide modules suitable for use with a mirror casing orhousing that includes the electrochromic element, which incorporates thereflective element and any associated components such as heater means,bezel means, electrically or manually operable actuation means, mountingmeans and electrical connection means. These components may bepre-assembled into a module that is substantially sealed from theoutside environment through the use of sealants like silicones, epoxies,epoxides, urethanes and the like. These components may also be formedand/or assembled in an integral molding process, such as with thoseprocesses described in U.S. Pat. No. 4,139,234 (Morgan) and U.S. Pat.No. 4,561,625 (Weaver), each of which describe suitable moldingprocesses in the context of modular window encapsulation. An added-valueelectrochromic mirror module, including the actuators which allowadjustment and selection of reflector field of view when mounted withinthe outside mirror housings attached to the driver-side andpassenger-side of a vehicle, may be pre-assembled and supplied tooutside vehicular mirror housing manufacturers to facilitate ease andeconomy of manufacturing.

[0228] Many aspects of the present invention, particularly thoserelating to the use of PRM and emitting displays; glass cover sheets,foils and the like; and thin film metal coatings that are appliedlocally and that are substantially reflecting and partiallytransmitting, may of course be employed with non-electrochromic rearviewmirrors for motor vehicles, such as conventional prismatic mirrors. Forinstance, with exterior rearview mirrors for motor vehicles, adriver-side rearview mirror and a passenger-side rearview mirror may bemounted in combination on a motor vehicle to be used to complement oneanother and enhance the driver's rearward field of view. One of suchmirrors may be an electrochromic mirror and the other mirror may be anon-electrochromic mirror, such as a chromed-glass mirror, with bothexterior mirrors benefitting from these aspects of the presentinvention. In addition, these aspects of the present invention may beemployed in connection with a display window that has been establishedin a prismatic mirror.

[0229] Substrate 2 may be of a laminate assembly comprising at least twotransparent panels affixed to one another by a substantially transparentadhesive material, such as an optical adhesive as described herein. Thislaminate assembly assists in reducing the scattering of glass shardsfrom substrate 2 should the mirror assembly break due to impact.Likewise, substrates 2,3 may each be of such a laminate assembly in aglazing, window, sun roof, display device, contrast filter and the like.

[0230] Also, the outermost surface of substrate 2 (i.e., the surfacecontacted by the outdoor elements including rain, dew and the like when,for example, substrate 2 forms the outer substrate of an interior orexterior rearview mirror for a motor vehicle constructed such as shownin FIGS. 1 to 13) can be adapted to have an anti-wetting property. Forexample, the outermost glass surface of an exterior electrochromicrearview mirror can be adapted so as to be hydrophobic. This reduceswetting by water droplets and helps to obviate loss in optical clarityin the reflected image off the exterior mirror when driven during rainand the like, caused by beads of water forming on the outermost surfaceof the exterior electrochromic mirror assembly. Preferably, theoutermost glass surface of the electrochromic mirror assembly ismodified, treated or coated so that the contact angle θ (which is theangle that the surface of a drop of liquid water makes with the surfaceof the solid anti-wetting adapted outermost surface of substrate 2 itcontacts) is preferably greater than about 90°, more preferably greaterthan about 120° and most preferably greater than about 150°. Theoutermost surface of substrate 2 may be rendered anti-wetting by avariety of means including ion bombardment with high energy, high atomicweight ions, or application thereto of a layer or coating (that itselfexhibits an anti-wetting property) comprising an inorganic or organicmatrix incorporating organic moieties that increase the contact angle ofwater contacted thereon. For example, a urethane coating incorporatingsilicone moieties (such as described in Lynam II, the disclosure ofwhich is hereby incorporated by reference) may be used. Also, to enhancedurability, diamond-like carbon coatings, such as are deposited bychemical vapor deposition processes, can be used as an anti-wettingmeans on, for example, electrochromic mirrors, windows and devices.

[0231] It is clear from the teaching herein that should a glazing,window, sun roof, display device, contrast filter and the like bedesirably constructed, the reflective element 8 need only be omittedfrom the assembled construction so that the light which is transmittedthrough the transparent substrate is not further assisted in reflectingback therethrough.

[0232] In the aspects of the present invention concerning electrochromicdevices, particularly electrochromic optical attenuating contrastfilters, such contrast filters may be an integral part of anelectrochromic device or may be affixed to an already constructeddevice, such as cathode ray tube monitors. For instance, an opticalattenuating contrast filter may be manufactured using an electrochromicelement as described herein and then affixing it to a device, using asuitable optical adhesive. In such contrast filters, the constituents ofthe electrochromic element should be chosen so that the contrast filtermay color to a suitable level upon the introduction of an appliedpotential thereto, and no undesirable spectral bias is exhibited.

[0233] Also, an electrochromic reflector according to this invention canbe used with a refracting means comprising a first refractor and asecond refractor. The first refractor diverts incident light towards theelectrochromic variably dimmable reflector. The second refractor ispositioned so that light from the first refractor is incident thereonand directs light from the electrochromic reflector towards the observer(typically, the driver of a motor vehicle). A refracting means suitablefor use in accordance with this invention is described in U.K. Patent GB2,254,832B for “A Rear View Mirror Unit”, the disclosure of which ishereby incorporated herein by reference.

[0234] A synchronous manufacturing process, such as the one representedin FIG. 15, may be used for the production of both interior and exteriorelectrochromic rearview mirrors. For example, uncoated glass shapes(which may be flat shapes, curved shapes or multi-radius shapes) alreadycut to the desired shape and size of the substrate 2 are loaded into theevaporative coater 1500 and a transparent conductor (such as indium tinoxide) is deposited thereon [such as by electron beam evaporation at arate of about 3-5 Å/sec using an oxygen backfill pressure within therange of from about 5×10⁻⁵ torr to about 9×10⁻⁴ torr oxygen partialpressure and with the substrate heated to a temperature within the rangeof about 200° C. to about 450° C.]. Synchronous with this deposition,uncoated glass shapes already cut to the desired shape and size of thesubstrate 3 are loaded into the evaporative coater 1510. An adhesionlayer of chromium, followed by a reflector layer of aluminum, followedby an electrochromic solid film layer of tungsten oxide are thendeposited thereon. After substrate coating is complete, the substrates2,3 pass to a seal dispensing station 1520 where a high speed,computer-controlled automatic fluid dispensing system (such as AUTOMOVE400) is used to dispense a latent cure, one-package epoxy around theedge periphery of the transparent conductor coated surface of thesubstrate 2. Next, and with the substrates 2,3 held in fixtures, therespective inwardly-facing surfaces are mated, with the weight of thefixture itself providing a temporary hold to keep the mated surfaces inplace. The sandwiched parts are then moved to a conveyorized oven orlehr 1530, where the latent curing agent in the latent cure epoxy isactivated by exposure to a temperature of at least about 110° C. Uponexiting the conveyorized oven or lehr 1530, the now permanently matedcell is removed from the fixtures (which are themselves reusable) andthe cell is filled and finished at the fill/assembly station 1540. Useof such a synchronous manufacturing process, and particularly when alatent cure epoxy is used which is dispensed by an automatic fluiddispenser, with the epoxy cured in a conveyorized oven or lehr, iswell-suited for economic, high volume, lean manufacturing of products,such as interior and exterior electrochromic rearview mirrors.

[0235] Many aspects of the present invention, especially thoseconcerning mirror construction, use of elemental semiconductor layers orstacks (with or without an additional undercoat of silicon dioxideand/or an overcoat of doped tin oxide), PRM, anti-wetting adaptation,synchronous manufacturing, localized thin film coatings, multi-layertransparent conducting stacks incorporating a thin metal layerovercoated with a conducting metal oxide layer, conducting seals,variable intensity band pass filters, isolation valve vacuumbackfilling, cover sheets and on demand displays, may of course beincorporated into electrochromic mirrors and electrochromic devices thatemploy electrochromic technology for the electrochromic elementdifferent from that which is taught and described herein, such aselectrochromic solution technology of the electrochemichromic type(e.g., Byker I, Byker II, Varaprasad I and Varaprasad III) andelectrochromic solid film technology (e.g., the '675 application, the'557 application and Lynam I), including electrochromic organic thinfilm technology, in which a thin film of organic electrochromic materialsuch as a polymerized viologen is employed in the electrochromic element[see e.g., U.S. Pat. No. 4,473,693 (Wrighton)].

[0236] Also, an electrochromic solid film may be used which is formed ofan inorganic metal oxide, such as a semiconductor electrode oftransparent polycrystalline titanium dioxide (TiO₂), to which isattached a redox species (such as a viologen).using a chelate (spacer)such as salicylic acid chemiabsorbed to the Tio₂ by chelation to surfaceTi⁴⁺ atoms. When such a solid film (such as is described in Marquerettazet al., J. Am. Chem. Soc., 116, 2629-30 (1994), the disclosure of whichis hereby incorporated herein by reference] is deposited (preferablywith a thickness of about 0.1 μm to about 10 μm) upon an electronicconducting layer, such as fluorine-doped tin oxide, an electron donor(TiO₂)—spacer (the salicylic acid bound to the TiO₂)—electron acceptor(the viologen bound to the salicylic acid) heterodyad is formed that iscapable of efficient electrochromic activity. Such donor-spacer-acceptorcomplexes can include multiple acceptors, such as may be formed when asecond acceptor (such as a quinone like anthraquinone) is linked to afirst acceptor (such as a viologen). Such a donor-spacer-acceptor solidfilm can function as an electrochromic solid film, and may beadvantageously employed in the electrochromic rearview mirrors, windows,sun roofs and other devices of this invention.

[0237] The electrochromic medium can comprise a variety ofelectrochromically active moieties attached, such as by chemicalbonding, to an organic or inorganic matrix, and/or included in a polymerstructure as electrochromically active sites. For example, anelectrochromically active phthalocyanine-based, and/orphthalocyanine-derived, moiety that, preferably, is color-fast and UVstable in both its reduced and oxidized state, can be included in theelectrochromic medium, preferably as part of a solid film.Electrochromically active phthalocyanines that can be incorporated in asolid, and/or formed as a solid, include transition metalphthalocyanines such as zirconium phthalocyanines and molybdenumphthalocyanines, such as described in J. Silver et al., Polyhedron,8(13/14), 1163-65 (1989), the disclosure of which is hereby incorporatedherein by reference; solid state polymerized phthalocyanines such as areformed by thermal polymerization of dihydroxy(metallo)phthalocyaninecompounds of Group IVa elements as disclosed by K. Beltios et al., J.Polym. Sci.: Part C: Polymer Letters, 27, 355-59 (1989), the disclosureof which is hereby incorporated herein by reference; siliconphthalocyanine-siloxane polymers such as described in J. Davison et al.,Macromolecules, 11(1), 186-91 (January-February 1978), the disclosure ofwhich is hereby incorporated herein by reference; and lanthanidediphthalocyanines such as lutetium diphthalocyanine such as described byG. Corker et al., J. Electrochem. Soc., 126, 1339-43 (1979), thedisclosure of which is hereby incorporated herein by reference. Suchphthalocyanine-based electrochromic media, preferably in solid form and,most preferably, UV stable in both their oxidized and reduced states,may be advantageously employed in the electrochromic rearview mirrors,windows, sunroofs, and other device of this invention.

[0238] Once constructed, the electrochromic device, such as anelectrochromic mirror, may have a molded casing or housing placedtherearound. This molded casing or housing may be pre-formed and thenplaced about the periphery of the assembly or, for that matter,injection molded therearound using conventional techniques, includinginjection molding of thermoplastic materials, such as polyvinyl chlorideor polypropylene, or reaction injection molding of thermosettingmaterials, such as polyurethane or other thermosets. These techniquesare well-known in the art [see e.g., Morgan and Weaver, respectively].

[0239] Also, where it is desirable to dispense a fluid medium, such as apotentially air-sensitive electrolyte, into the cell cavity (orinterpane spacing) formed between substrates 2 and 3 in an emptyelectrochromic cell (such as an empty electrochromic rearview mirrorcell), a vacuum backfilling method, such as described in Varaprasad IV,may be used.

[0240] For example, a vacuum backfill apparatus can be configured with afirst bell-jar chamber capable of receiving an empty electrochromicrearview cell and a second chamber, separate from the first bell-jarchamber. The second chamber includes a container, such as a crucible,which holds the potentially air-sensitive electrolyte to be filled intothe empty interpane cavity of the electrochromic mirror cell in thebell-jar chamber. The second chamber is initially maintained at anatmospheric pressure of inert gas (such as nitrogen). An isolation valve(such as a gate valve) separates this second inert gas-filled chamberfrom the first bell-jar chamber, that itself is initially at anatmospheric pressure of ordinary air. After loading an empty cell intothe first bell-jar chamber, a vacuum pump is used to evacuate the airtherefrom to create a high vacuum (i.e., a low partial pressure of thecomponents of air such as oxygen, water vapor, carbon dioxide, nitrogen,etc.) within the first bell-jar chamber. A high vacuum is also createdwithin the interpane cavity of the rearview mirror empty cell in the nowevacuated first bell-jar chamber. Next, and only when the air within thebell-jar chamber has been substantially removed, the isolation valvebetween the bell-jar chamber and the electrolyte-containing crucible inthe second chamber is opened. The vacuum pump now pumps on the secondchamber to pump away the inert gas therein. As a result, both thebell-jar chamber and the second chamber are brought to a high vacuum.

[0241] Procedures described in Varaprasad IV for backfilling are nowfollowed. During the venting step, the bell-jar chamber/second chamberis vented to an atmospheric pressure of inert gas (such as nitrogen).The isolation valve is then closed, once again isolating the secondchamber (now refilled with inert gas) from the bell-jar chamber. Oncethe second chamber is again isolated, the bell-jar chamber is opened toan ordinary room air atmosphere and the now-filled mirror cell isremoved.

[0242] In such a vacuum backfilling technique using an isolation valvemeans, backfilling occurs using an inert gas but the use of an isolationvalve (such as a gate valve, sluice valve, port valve, slit valve orequivalent isolation valve) isolates the potentially air-sensitiveelectrolyte from the air atmosphere at those times when the empty cellis inserted, and the filled cell is removed, from the bell-jar chamber.Such use of an isolation valve means during vacuum backfilling using aninert gas allows for the bell-jar chamber to be loaded and unloaded inan ordinary room air environment, while protecting the potentiallyair-sensitive electrolyte from exposure to air. In such an isolationvalve vacuum backfilling apparatus, a suitable dispenser can be used toreplenish the crucible with electrolyte, with the electrolyte beingpumped from an electrolyte reservoir that is maintained under air-tightconditions without being exposed to air. With this arrangement, theelectrolyte is replenished without being exposed to air. Also, as analternative to flooding the second chamber with inert gas when theisolation valve is closed (so as to isolate the electrolyte in thesecond chamber from contact with air), a vacuum can be established(and/or maintained) in this second chamber when the isolation valve isclosed.

[0243] Each of the documents cited herein is hereby incorporated byreference to the same extent as if each document had individually beenincorporated by reference.

[0244] In view of the above description of the instant invention, it isevident that a wide range of practical opportunities is provided by theteaching herein. The following examples of electrochromic mirrors andelectrochromic devices are provided to illustrate the utility of thepresent invention only and are not to be construed so as to limit in anyway the teaching herein.

EXAMPLES

[0245] Example 1

[0246] An electrochromic interior rearview automotive mirror cell havinga shape commonly used for interior rearview mirrors was constructed fromclear HW-ITO-coated glass as the first substrate (having a sheetresistance of about 12 ohms per square), with a tungsten oxideelectrochromic solid film coated over its HW-ITO coating (which iscoated onto the inward surface of the substrate). As the secondsubstrate of the mirror cell, a HW-ITO-coated glass substrate (alsohaving a sheet resistance of about 12 ohms per square) with the ITOcoated onto its inward surface was used. A reflective element was formedby coating a layer of silver onto the rearmost (opposite, non-inward)surface of the second substrate of the mirror cell. The HW-ITO wascoated onto the glass substrates at a thickness of about 1,500 Å; thetungsten oxide electrochromic solid film was coated over the HW-ITOcoating of the first substrate at a thickness of about 5,000 Å; and thesilver was coated onto the rearmost surface of the second substrateusing conventional wet chemical silver line deposition as known in themirror art. The first substrate was positioned in spaced-apartrelationship with the second substrate to form a 88 μm interpane spacingbetween the coated inward surfaces of the substrates. The firstsubstrate was also laterally displaced from the second substrate toprovide a convenient area for bus bar attachment.

[0247] We formulated an electrolyte for this mirror cell containingferrocene (about 0.015 M), phenothiazine (about 0.06 M), lithiumperchlorate (about 0.05 M) and “UVINUL” 400 [about 5% (w/v)] in asolvent combination of tetramethylene sulfone and propylene carbonate[in a ratio of about 50:50 (v/v)].

[0248] We dispensed the electrolyte described above into the mirror cellby the vacuum backfilling method [as described in Varaprasad IV].

[0249] Upon application of about 1.4 volts, we observed that the mirrordimmed uniformly and rapidly to a neutral gray colored state.Specifically, we observed that the mirror dimmed from about 70%reflectance to about 20% reflectance in a response time of about 3.2seconds. In addition, we observed that the mirror exhibited a highreflectance in the unpowered, bleached state of about 74.7% and a lowreflectance in the dimmed state of about 5.9%

[0250] We made and recorded these observations following the standardprocedure J964A of the Society of Automotive Engineers, using areflectometer—set in reflectance mode—equipped with a light source(known in the art as Standard Illuminant A) and a photopic detectorassembly.

[0251] Spectral scans were recorded using a conventionalspectrophotometer operating in reflection mode in both the bleachedstate [see FIG. 1 and Tables II(a) and II(b)] and the colored state atan applied potential of about 1.5 volts [see FIG. 2 and Tables III(a)and III(b)]. TABLE II(a) Reflectance Data In The Unpowered. BleachedState WL (nm) 0 5 10 15 20 25 30 35 40 45 380 14.5 20.4 29.1 38.2 45.951.7 56.1 59.5 61.9 64.2 430 65.9 67.7 68.9 70.4 71.6 72.7 73.6 74.875.4 76.2 480 77.0 77.7 78.1 78.9 79.5 80.2 80.6 80.7 80.7 80.9 530 80.780.6 80.0 80.1 79.4 79.3 78.8 78.5 78.1 77.8 580 77.2 76.9 76.5 75.875.1 74.5 74.1 73.5 72.5 71.9 630 71.4 70.6 70.1 69.4 68.7 67.9 67.266.5 65.6 64.9 680 64.5 63.6 62.9 62.0 61.3 60.6 60.2 59.6 58.6 57.4 73057.1 56.6 55.7 55.0 54.6 53.9 52.5 51.6 51.2 50.7 780 50.5

[0252] TABLE II(b) Color Statistics - C.I.E. Convention Using 2 DegreeEye Illuminant x y DomWave Purity Y A 0.4422 0.4172 547.0 3.2 77.0 C0.3097 0.3304 549.7 3.8 77.8

[0253] TABLE III(a) Reflectance in the Colored State at 1.5 Volts WL(nm) 0 5 10 15 20 25 30 35 40 45 380 11.4 11.6 11.8 11.5 10.6 9.5 8.67.7 6.8 6.1 430 5.5 5.0 5.0 5.1 5.6 5.6 5.8 6.0 6.2 6.3 480 6.5 6.7 6.86.9 7.0 7.1 7.2 7.2 7.2 7.3 530 7.4 7.6 7.8 8.0 8.1 8.1 8.0 7.8 7.6 7.4580 7.3 7.0 6.8 6.6 6.3 6.1 6.0 5.7 5.6 5.4 630 5.4 5.2 5.2 5.1 5.0 4.94.9 4.8 4.8 4.8 680 4.8 4.8 4.8 4.7 4.8 4.8 4.8 4.8 4.8 4.8 730 4.9 4.94.9 3.0 5.1 5.0 5.1 5.2 5.1 5.2 780 5.4

[0254] TABLE III(b) Color Statistics -- C.I.E. Convention Using 2 DegreeEye at 1.5 Volts Illuminant x y DomWave Purity Y A 0.4323 0.4342 545.38.5 7.0 C 0.3098 0.3499 549.3 8.9 7.1

[0255] We also cycled the mirror as described in Table IV below. TABLEIV Number of Cycle Color/Bleach Cycles Temperature (° C.) Cycle (secs)Voltage 30,000 50 5/5 1.4/0.0 40,000 room 5/5 1.4/0.0 temperature 30,000−30 5/5 1.4/0.0 90,000 50 5/5 1.6/0.0 11,000 80 30/30 1.4/0.0

[0256] After subjecting this mirror to such cycling conditions, weobserved the reflectance of the mirror to decrease from about 70% toabout 20% in a response time of about 3.2 seconds. In addition, weobserved the mirror to have a high reflectance in the unpowered,bleached state of about 78.6% and a low reflectance in the dimmed stateof about 6.4% when a potential of 1.4 volts was applied thereto. We madeand recorded these observations using the SAE procedure referred tosupra.

[0257] We observed that these mirrors exhibited excellent stability totemperature extremes. For example, after storage at temperatures in the80 C.-110° C. range, for periods ranging from about 2 hours to in excessof 336 hours, performance remained excellent, and, indeed, in aspectssuch as transition times from low to high reflectance states performancewas even better after heat exposure.

Example 2

[0258] In this example, we used the same electrolyte formulation and anelectrochromic mirror constructed in the same manner as in Example 1,supra.

[0259] We introduced an applied potential of about 1.4 volts to themirror and observed its center portion to change from a high reflectanceof about 75.9% to a low reflectance of about 6.3%, which decreased fromabout 70% reflectance to about 20% reflectance in a response time ofabout 3.5 seconds.

[0260] We then subjected this mirror to an accelerated simulation ofoutdoor weathering conditions to investigate its resilience andstability to ultraviolet light. Specifically, we subjected the mirror toabout 1300 KJ/m² of ultraviolet exposure in an Atlas Ci35A XenonWeather-o-meter (Atlas Electric Devices Company, Chicago, Ill.),equipped with a Xenon lamp emitting about 0.55 w/m² intensity at about340 nm. After accelerated outdoor weathering, we observed that themirror continued to function suitably for use in a motor vehicle. Wealso observed that the mirror cycled well. In addition, we observed thehigh reflectance to be about 75.2% and the low reflectance to be about6.9% when a potential of about 1.4 volts was applied thereto.

[0261] We made and recorded these observations using the SAE procedurereferred to in Example 1, supra.

Example 3

[0262] The electrochromic mirror cell of this example was constructedfrom clear HW ITO-coated glass as the first substrate as in Example 1,supra. However, the second substrate was constructed of ordinarysoda-lime glass. Using electron beam evaporation in a vacuum chamber, alayer of chromium was coated directly onto the inward surface of thesecond glass substrate as an adhesion promoter. Next, and withoutbreaking vacuum, a thin film of silver was coated onto the layer ofchromium as a reflective element, and thereafter (again without breakingvacuum) tungsten oxide was coated over the layer of silver as anelectrochromic solid film. The layer of chromium was coated onto thesecond substrate at a thickness of about 1,000 Å; the thin film ofsilver was coated over the chromium at a thickness of about 1,000 Å; andthe tungsten oxide was coated over the silver at a thickness of about5,000 Å. The sheet resistance of the silver so undercoated with chromiumwas about 0.4 to 0.5 ohms per square. As with the mirror cell of Example1, supra, the first substrate was positioned in spaced-apartrelationship with the second substrate to form an 88 μm interpanespacing between the coated inward surfaces of the substrates. The firstsubstrate was laterally displaced from the second substrate to provide aconvenient area for bus bar attachment.

[0263] We used the electrolyte of Example 1, supra, and dispensed itinto the mirror cell using the vacuum backfilling method [as describedin Varaprasad IV].

[0264] We introduced an applied potential of about 1.4 volts to themirror and observed the change from a high reflectance of about 81.6% toa low reflectance of about 5.9%, which decreased from about 70%reflectance to about 20% reflectance in a response time of about 1.9seconds.

[0265] We made and recorded these observations using the SAE procedurereferred to in Example 1, supra.

[0266] We also cycled the mirror as described in Table V below. TABLE VNumber of Cycle Color/Bleach Cycles Temperature (° C.) Cycle (secs)Voltage 30,000 50 5/5 1.4/0.0 40,000 room 5/5 1.4/0.0 temperature

[0267] After subjecting the mirror to such cycling conditions, weobserved the reflectance of the mirror in the unpowered, bleached stateto be 77.3%, and the mirror dimmed to 6.2% reflectance with 1.4 voltsapplied thereto.

Example 4

[0268] We used an electrochromic mirror cell constructed in the sameformat and with the same shape and dimensions as in Example 1, supra,except that a tungsten oxide electrochromic solid film (having athickness of about 5,000 Å) was coated over the HW-ITO coating on theinward surface of the second substrate.

[0269] We formulated an electrolyte containing ferrocene (about 0.025M), phenothiazine (about 0.05 M), lithium perchlorate (about 0.05 M) and“UVINUL” 400 [about 10% (w/v)] in a solvent combination oftetramethylene sulfone and propylene carbonate [in a ratio of about25:75 (v/v)]. We dispensed the electrolyte into the mirror cell usingthe vacuum backfilling method [as described in Varaprasad IV].

[0270] Upon introduction of an applied potential of about 1.4 volts, weobserved the mirror to dim uniformly and rapidly to a neutral graycolored state. Specifically, we observed the mirror to have a highreflectance in the unpowered, bleached state of about 70.7% and a lowreflectance in the dimmed state of about 7.3%. We made and recordedthese observations using the SAE procedure referred to in Example 1,supra.

[0271] We also cycled the mirror and subjected the mirror to anaccelerated simulation of outdoor weathering conditions to investigateits resilience and stability to ultraviolet light as described inExample 2, supra, but at an exposure of about over 2,500 KJ/m². Weobserved that the mirror cycled well, and after accelerated outdoorweathering, we also observed that the mirror continued to function in amanner suitable for use in a motor vehicle.

Example 5

[0272] In this example, we fabricated an electrochromic glazing cell ofa construction suitable for use as a window or a sun roof for a motorvehicle. The glazing cell was dimensioned to about 15 cm×about 15 cm,with an interpane spacing between the tungsten oxide coating on theinward surface of the second substrate and the HW-ITO coating on theinward surface of the first substrate of about 105 μm.

[0273] The glazing cell was constructed using spacers to assist indefining the interpane spacing. The spacers were sprinkled over thetungsten oxide-coated surface of the first substrate and, inward fromthe peripheral edge of the HW-ITO-coated second substrate, an epoxy wasapplied using a silk-screening technique. While the epoxy was stilluncured, the first substrate and the second substrate were off-set fromone another by a lateral displacement and a perpendicular displacement.The epoxy was then cured into a seal for the electrochromic glazing cellusing a vacuum bagging technique (as is known in the laminating art) ata reduced atmospheric pressure of about 10″ of mercury and a temperatureof about 110° C. for a period of time of about 2 hours in order toachieve substantially even pressure while curing the epoxy into a seal.

[0274] We formulated an electrolyte containing ferrocene (about 0.015M), phenothiazine (about 0.06 M), lithium perchlorate (about 0.05 M) and“UVINUL” 400 [about 5% (w/v)] in a solvent combination of tetramethylenesulfone and propylene carbonate [in a ratio of about 50:50 (v/v)]. Wedispensed this electrolyte into the electrochromic glazing cell usingthe vacuum backfilling method [as described in Varaprasad IV].

[0275] Upon introduction of an applied potential of about 1.4 volts tothe electrochromic glazing, we observed the transmissivity change from ahigh transmittance of about 78.6% to a low transmittance of about 12.9%.

[0276] We made and recorded these observations using the SAE procedurereferred to in Example 1, supra, except that the reflectometer was setin transmittance mode.

Example 6

[0277] In this example, we constructed an electrochromic mirror suitablefor use as an exterior rearview mirror for a motor vehicle.

[0278] The mirror was constructed from clear HW-ITO-coated glass as thefirst substrate as in Example 1, supra.

[0279] However, as the second substrate we used ordinary soda-limeglass. Both substrates were sized and shaped to dimensions of 9.5 cm×15cm. A notch was cut in one edge of the first substrate, and anothernotch was cut in a different location on one edge of the secondsubstrate. A bus bar was formed along the edges of the first substrateby silk-screening a silver conductive frit material [#7713 (Du Pont)]all around the perimetal region of the HW-ITO-coated surface of thesubstrate to a width of about 2.5 mm, and then firing the frit at anelevated temperature in a reducing atmosphere to avoid oxidizing theHW-ITO.

[0280] A layer of chromium at a thickness of about 1,000 Å was coateddirectly by vacuum deposition onto the inward surface of the secondglass substrate as an adhesion promoter. Thereafter, without breakingvacuum, a thin film of silver at a thickness of about 1,000 Å was coatedonto the layer of chromium as a reflective element, and tungsten oxideat a thickness of about 5,000 Å was then coated (again, without breakingvacuum) over the layer of silver as an electrochromic solid film. Thefirst substrate and the second substrate were then positioned inspaced-apart relationship so that the edges of the substrates wereflush, and a seal was applied so as to form a cavity between the twosubstrates. In this flush design, the interpane spacing between thecoated inward surfaces of the substrates was 88 μm.

[0281] For this exterior mirror, we formulated an electrolyte containingferrocene (about 0.025 M), phenothiazine (about 0.06 M), lithiumtetrafluoroborate (about 0.05 M) and “UVINUL” 400 [about 5% (w/v)] inpropylene carbonate. We dispensed this electrolyte into the mirror cellusing the vacuum backfilling method [as described in Varaprasad IV].

[0282] Electrical leads were then attached to the mirror. The notch onthe second substrate permitted an electrical lead to be attached at apoint contact on the silver frit bus bar formed around and substantiallycircumscribing the perimeter of the HW-ITO-coated inward surface of thefirst substrate. Another electrical lead was attached to the portion ofthe chromium/silver/tungsten oxide coating on the inward surface of thesecond substrate exposed by the notch cut in the first substrate. Thepoint contact was sufficient to apply a potential across the electrodesbecause of the low sheet resistance of the coating on the inward surfaceof the second substrate.

[0283] Upon introduction of an applied potential of about 1.5 volts tothe mirror, we observed the reflectance change from a high reflectanceof about 77.5% to a low reflectance of about 10.6%.

[0284] We also cycled the mirror for about 50,000 cycles at atemperature of about 50° C., and observed that the mirror cycled welland continued to function suitably for use in a motor vehicle.

Example 7

[0285] In this example, we used the same electrolyte formulation and anelectrochromic mirror cell of the same shape as described in Example 1,supra. After filling the electrochromic mirror cell using the vacuumbackfilling method [as described in Varaprasad IV], we removed thetungsten oxide coating from the peripheral edge of the first substrateusing a dilute basic solution of potassium hydroxide followed by water.We then connected the bus bars to this newly-exposed ITO surface.Thereafter we applied a secondary weather barrier material. Thesecondary weather barrier material was formed from “ENVIBAR” UV 1244Tultraviolet curable epoxy, with about 2% of the silane coupling agentA-186 (OSi Specialties Inc., Danbury, Conn.) combined with about 1% ofthe photoinitiator “CYRACURE” UVI-6990. Thereafter, we cured thismaterial by exposing it to a suitable source of ultraviolet light toform a secondary weather barrier.

[0286] Once the secondary weather barrier was formed, we introduced anapplied potential of about 1.3 volts to the mirror and observed thereflectance change from a high reflectance of about 77.8% to a lowreflectance of about 7.1%.

[0287] We made and recorded these observations using the SAE procedurereferred to in Example 1, supra.

[0288] We also mounted this electrochromic mirror in the cabin of amotor vehicle and found the mirror to operate in a commerciallyacceptable manner.

Example 8

[0289] We used an electrochromic mirror cell having the same shape asdescribed in Example 1, supra, constructed from clear ITO-coated glassas the first substrate (having a sheet resistance of about 80 ohms persquare). As the second substrate of the mirror cell, we used ordinarysoda-lime glass. The first substrate was dimensioned about 2 to about 3mm larger in both length and width than the second substrate. A layer ofchromium, as an adhesion promoter, was coated directly onto the inwardsurface of the second glass substrate at a thickness of about 1,000 Å. Athin film of silver, as a reflective element, was thereafter coated ontothe layer of chromium at a thickness of about 1,000 Å and tungstenoxide, as an electrochromic solid film, was then coated over the layerof silver at a thickness of about 5,000 Å. These thin films were coatedin a vacuum deposition process by electron beam evaporation and weredeposited in a unitary deposition process without breaking vacuum duringdeposition of the chromium/silver/tungsten oxide stack.

[0290] Also, when a transparent conductor coated substrate (for example,fluorine doped tin oxide coated glass, such as “TEC-Glass” describedsupra, that is bendable in an ordinary air atmosphere) is used for thesubstrate 2, and/or when a bendable reflector-coated substrate (forexample, the combination of a silicon based reflector overcoated with atin oxide transparent conductor described supra), is used for thesubstrate 3, the process outlined in FIG. 15 can be appropriatelymodified. For example, a convex or aspherical exterior mirror shapesuitable for use as the substrate 2 can be cut from a bent minilite of“TEC-20” glass comprising a fluorine doped tin oxide transparentconductor of about 20 ohms per square sheet resistance and with the tinoxide coating located on the concave surface of the bent minilite. Useof such air-bendable transparent conductors, as are conventionallyknown, is an alternate to transparent conductor coating the concavesurface of a bent, plain glass surface, as illustrated in FIG. 15. Also,use of a bendable, elemental semiconductor reflector layer that isitself rendered conducting, or that is overcoated with a transparentconducting layer such as tin oxide, may be used (in lieu of coatingmetal layers of aluminum, silver, chromium and the like that aretypically non-bendable) on the convex surface of bent substrate 3.

[0291] The first substrate and the second substrate were positioned inspaced-apart relationship to form a 88 μm interpane spacing between theITO-coated surface of the first substrate and the multi-layered surfaceof the second substrate. The size and shape differential between thefirst substrate and the second substrate allowed the ITO-coated surfaceof the first substrate to extend beyond the multi-layered surface of thesecond substrate. Bus bars were attached substantially all around theperipheral edge of the ITO-coated first substrate onto which wereconnected the electrical leads. On the multi-layered second substrate,we attached electrical leads at a smaller portion thereof, such as at amere point contact.

[0292] We formulated an electrolyte containing ferrocene (about 0.015M), phenothiazine (about 0.06 M), lithium perchlorate (about 0.05 M) and“UVINUL” 400 [about 5% (w/v)] in a solvent combination of tetramethylenesulfone and propylene carbonate [in a ratio of about 50:50 (v/v)]. Wedispensed this electrolyte into the mirror cell using the vacuumbackfilling method [as described in Varaprasad IV].

[0293] Upon introduction of an applied potential of about 1.4 volts, weobserved the mirror to dim uniformly and rapidly to a neutral graycolored state. Specifically, we observed the mirror to have a highreflectance in the unpowered, bleached state of about 75.8% and a lowreflectance in the dimmed state of about 9.5%. We made and recordedthese observations using the SAE procedure referred to in Example 1,supra.

Example 9

[0294] In this example, we used the electrolyte formulation and anelectrochromic mirror having the same shape as described in Example 8,supra. However, the mirror of this example was constructed fromITO-coated glass as the first substrate having a sheet resistance ofabout 55 ohms per squares. In addition, the first substrate and thesecond substrate were positioned in spaced-apart relationship to form a63 μm interpane spacing between the ITO-coated surface of the firstsubstrate and multi-layered surface of the second substrate.

[0295] After dispensing the electrolyte into the mirror cell using thevacuum backfilling method [as described in Varaprasad IV], we observedthe mirror to have a high reflectance of about 75.7% and a lowreflectance of about 8.6% when a potential of about 1.4 volts wasapplied thereto. We made and recorded these observations using the SAEprocedure referred to in Example 1, supra.

Example 10

[0296] In this example, we fabricated an electrochromic glazing deviceof a construction suitable for use as a window or a sun roof on a motorvehicle containing a solid electrolyte. The glazing device wasdimensioned to about 15 cm×about 15 cm, with an interpane spacingbetween the tungsten oxide coating on the inward surface of the firstsubstrate and the HW-ITO coating on the inward surface of the secondsubstrate of about 74 μm.

[0297] The glazing device was constructed using spacers to assist indefining the interpane spacing. The spacers were sprinkled over thetungsten oxide coated surface of the first substrate and an epoxy wasapplied inward from the peripheral edge of the HW-ITO coated secondsubstrate using a silk-screening technique. While the epoxy was stilluncured, the first substrate and the second substrate were off-set fromone another by a lateral displacement and a perpendicular displacement.The weather barrier of the electrochromic glazing device was then formedby thermal curing using a vacuum bagging technique (as is known in thelaminating art) at a reduced atmospheric pressure of about 10″ ofmercury and a temperature of about 140° C. for a period of time of about1 hour in order to maintain a substantially even pressure when curingthe epoxy into a weather barrier.

[0298] We prepared a formulation of starting components containingferrocene [about 0.3% (w/w)], phenothiazine [about 0.8% (w/w)], lithiumperchlorate [about 0.4% (w/w)], “SARBOX” acrylate resin (500E50) [about27.9% (w/w)], propylene carbonate (as a plasticizer) [about 67.3% (w/w)]and “IRGACURE” 184 (as a photoinitiator) [about 3.3% (w/w)]. Wedispensed this formulation into the electrochromic glazing device usingthe vacuum backfilling method [as described in Varaprasad IV].

[0299] We then in situ polymerized the formulation by exposing it toultraviolet radiation to form a solid-phase electrolyte.

[0300] We then affixed bus bars along the peripheral edges of theelectrochromic glazing device, and connected electrical leads to the busbars. We introduced an applied potential of about 1.5 volts to theelectrochromic glazing for a period of time of about 2 minutes, with thepositive polarity applied at the second substrate (the surface of whichhaving tungsten oxide overcoated onto its HW-ITO-coated surface) andobserved it to have a high transmittance of about 73.0%. Thereafter, wereversed the polarity, and observed the transmission to dim to a lowtransmittance of about 17.8% when a potential of about 1.5 volts wasapplied thereto.

[0301] We made and recorded these observations using the SAE procedurereferred to in Example 1, supra, except that the reflectometer was setin transmittance mode.

Example 11

[0302] In this example, we constructed an electrochromic mirror devicehaving the same shape described in Example 1, supra, with an interpanespacing of about 74 μm and using a solid-phase electrolyte.

[0303] We prepared a formulation of starting components containingferrocene [about 0.2% (w/w)], phenothiazine [about 0.5% (w/w)], lithiumperchlorate [about 0.3% (w/w)], polyethylene glycol dimethacrylate (600)(PEGDMA-600) [about 17.9% (w/w)], propylene carbonate (as a plasticizer)[about 76.5% (w/w)], “IRGACURE” 184 (as a photoinitiator) [about 2.1%(w/w)] and “UVINUL” 400 [about 2.5% (w/w)].

[0304] The mirror was constructed using spacers to assist in definingthe interpane spacing. The spacers were sprinkled over the HW-ITO coatedinward surface of the first substrate (whose opposite, non-inwardsurface had been coated with a layer of silver using conventional wetchemical silver line deposition) and the formulation, which would betransformed into a solid-phase electrolyte, was dispensed thereover. Thesecond substrate, whose inward surface was coated with tungsten oxide ata thickness of about 5,000 Å, was positioned over the spacer-sprinkledHW-ITO coated surface of the first substrate to allow the formulation tospread evenly across and between the coated surfaces of the firstsubstrate and the second substrate.

[0305] We temporarily held the first substrate and the second substratetogether using clamps and in situ polymerized the formulation locatedtherebetween through exposure to ultraviolet radiation to form asolid-phase electrolyte. Specifically, we placed the mirror onto theconveyor belt of a Fusion UV Curing System F-450 B, with the beltadvancing at a rate of about fifteen feet per minute and being subjectedto ultraviolet radiation generated by the D fusion lamp of the F-450 B.We passed the mirror under the fusion lamp fifteen times pausing for twominute intervals between every fifth pass.

[0306] We then affixed bus bars along the peripheral edges of thedevice, and attached electrical leads to the bus bars.

[0307] We introduced an applied potential of about 1.5 volts to theelectrochromic mirror for a period of time of about 2 minutes, with thepositive polarity applied at the second substrate (the surface of whichhaving tungsten oxide overcoated onto its HW-ITO-coated surface) andobserved it to have a high reflectance of about 73.2%. Thereafter, wereversed the polarity, and observed the reflection to dim to a lowreflectance of about 7.1% when a potential of about 1.5 volts wasapplied thereto.

[0308] We made and recorded these observations using the SAE procedurereferred to in Example 1, supra.

Example 12

[0309] In this example, we constructed an electrochromic mirror cellhaving the same shape described in Example 4, supra.

[0310] We formulated an electrolyte containing ferrocene (about 0.025M), phenothiazine (about 0.06 M), lithium perchlorate (about 0.05 M) and“UVINUL” 400 [about 5% (w/v)] in a solvent combination of 1,2-butylenecarbonate and propylene carbonate [in a ratio of about 50:50 (v/v)]. Wedispensed this electrolyte into the mirror cell using the vacuumbackfilling method [as described in Varaprasad IV].

[0311] Upon introduction of an applied potential of about 1.4 volts tothe mirror, we observed the high reflectance change from about 72.0% toa low reflectance of about 6.8%.

[0312] We also cycled the mirror for about 50,000 cycles at atemperature of about 50° C., and observed it to cycle well.

Example 13

[0313] In this example, we again constructed an electrochromic mirrorcell having the same shape described in Example 1, supra.

[0314] For this mirror cell, we formulated an electrolyte containingferrocene (about 0.025 M), phenothiazine (about 0.06 M), lithiumperchlorate (about 0.05 M), lithium tetrafluoroborate (about 0.05 M) and“UVINUL” 400 [about 5% (w/v)] in propylene carbonate, and dispensed itinto the mirror cell using the vacuum backfilling method [as describedin Varaprasad IV].

[0315] Upon introduction of an applied potential of about 1.4 volts tothe mirror, we observed the high reflectance to change from about 72.0%to a low reflectance of about 6.7%.

[0316] The mirror demonstrated excellent cycle stability and stabilityto ultraviolet light.

Example 14

[0317] In this example, we constructed an electrochromic mirror cellhaving the same shape described in Example 1, supra, with an on demanddisplay. For illustrative purposes, see FIG. 9.

[0318] To provide the on demand display to this mirror cell, a displaywindow (with dimensions of about {fraction (7/16)}″×¾″) was laser-etchedthrough an overcoating of silver/copper/paint on the rearmost (opposite,non-inward) surface of the second substrate of the mirror cell.

[0319] Over and within the display window, we applied an opticaladhesive [“IMPRUV” LV potting compound (commercially available fromLoctite Corporation, Newington, Conn.)] so that a glass cover sheet,having a thickness of about 0.075″, may be disposed over and affixedthereto.

[0320] The glass cover sheets suitable for use in this context wereprepared by previously exposing a larger glass sheet to a vacuumevaporation process in which a thin film layer of silver was coated ontoone of its surfaces. The thin film layer of silver was substantiallyreflecting (having a reflectance of about 93%) and partiallytransmitting (having a transmittance of about 5%). The silver-coatedglass cover sheet was then cut to size—e.g., about 1″×¾″—, and thesilvered-surface disposed over, and affixed to using the opticaladhesive, the display window. Over the opposite, non-silvered surface ofthe glass cover sheet, we placed a layer of epoxy [UV15-74RI(commercially available from Master Bond Incorporated, Hackensack,N.J.)] and affixed thereto a vacuum fluorescent display [Part No.FIP2QM8S (NEC Electronics Incorporated, Mountain View, Calif.)].

[0321] Into this mirror cell, we dispensed the electrolyte of Example 1,supra.

Example 15

[0322] In this example, we constructed an electrochromic mirror cellhaving the same shape described in Example 1, supra, with an on demanddisplay. For illustrative purposes, see FIG. 10.

[0323] In this mirror cell, like the mirror cell of Example 14, supra, adisplay window (with dimensions of about {fraction (7/16)}″×¾″) waslaser-etched through the silver/copper/paint overcoating of the rearmost(opposite, non-inward) surface of the second substrate of the mirrorcell.

[0324] A thin film layer of silver was then coated over the displaywindow so formed by electron beam evaporation in a vacuum chamber asdescribed supra. The thin film layer of silver was substantiallyreflecting (having a reflectance of about 90%) and partiallytransmitting (having a transmittance of about 8%).

[0325] Over and within the silvered-display window, we applied a layerof epoxy [UV15-74RI (Master Bond)] and affixed thereto a vacuumfluorescent display [Part No. FIP2QM8S (NEC Electronics)].

[0326] Into this mirror cell, we dispensed the electrolyte of Example 1,supra.

Example 16

[0327] In this example, we constructed an electrochromic mirror cellusing as the first substrate and second substrate clear HW-ITO-coatedglass. Over the inward surface of the second substrate, we coated alayer of chromium at a thickness of about 100 Å as an adhesion promoter.We then coated a thin film of silver at a thickness of about 450 Å ontothe layer of chromium as a reflective element, and a layer of tungstenoxide at a thickness of about 5,800 Å over the layer of silver as anelectrochromic solid film. The first substrate and the second substratewere positioned in spaced-apart relationship to form an 88 μm interpanespacing between the coated inward surfaces of the substrates.

[0328] We placed an opaque tape on the rearmost surface of the secondsubstrate with apertures provided therein at appropriate locations toaccommodate vacuum fluorescent displays and other information indicia.

[0329] A vacuum fluorescent display was affixed to this mirror cell asdescribed in Example 14, supra, but dispensing with the reflector coatedcover sheet. The display provided compass directional information and,dependent on the vehicle direction when driving, displayed N, NE, E, SE,S, SW, W or NW when any one of which coordinates was activated bycompass circuitry included in the mirror housing and assembly into whichthe electrochromic mirror element was mounted for driving in a vehicle,and such as described in commonly assigned U.S. Pat. No. 5,255,442(Schierbeek). Turn signal indicia [JKL NEO-Wedge Lamps T2-1/4(commercially available from JKL Components Corporation, Paloina,Calif.)] were also located behind the rearmost surface of the secondsubstrate, with appropriately shaped apertures cut into the opaque tapeat the location of the turn signal indicia. The turn signal indicia wasactivated through a triggering mechanism from the particular turnsignal. For an illustration of the use of turn signal indicia 21 in anelectrochromic mirror, see FIG. 12.

[0330] Into this mirror cell, we dispensed the electrolyte of Example 1,supra.

[0331] Upon introduction of an applied potential of about 1.4 volts tothe mirror, we observed the high reflectance to change from about 74.1%to a low reflectance of about 7.0%. We also observed the transmittanceto be about 4.5% in the clear state.

[0332] This mirror was installed in a vehicle and tested under a varietyof actual day and night driving conditions, and was found to operate forits intended purpose.

Example 17

[0333] In this example, we constructed an electrochromic mirror suitablefor use as an interior rearview mirror for a motor vehicle.

[0334] The mirror was constructed from clear ITO-coated glass as thefirst substrate (having a sheet resistance of about 80 ohms per square).As the second substrate of the mirror cell we used ordinary soda-limeglass. Both substrates were sized and shaped to identical dimensions. Anotch was cut in the middle of the top edge of the first substrate andanother notch was cut in the middle of the bottom edge of the secondsubstrate. A thin metal film bus bar was formed along the edges of thefirst substrate by first affixing a mask over the central region leavingmost of the perimeter region unmasked, and then depositing by a vacuumevaporation process a thin film of chromium having a thickness of about2,000 Å followed by a thin film of silver having a thickness of about5,000 Å.

[0335] A layer of chromium at a thickness of about 1,000 Å was coateddirectly onto the inward surface of the second glass substrate as anadhesion promoter. A thin film of silver at a thickness of about 1,000 Åwas then deposited onto the layer of chromium as a reflective elementand tungsten oxide at a thickness of about 5,000 Å was then coated overthe layer of silver as an electrochromic solid film.

[0336] The first substrate and the second substrate were then positionedin a spaced-apart relationship so that the edges of the substrates wereflush and a seal was applied to form a cavity between the substrates. Inthis flush design, the interpane spacing between the coated inwardsurfaces of the substrates was 88 μm.

[0337] For this flush design interior mirror, we formulated anelectrolyte as in Example 1, supra. We dispensed this electrolyte intothe mirror cell using the vacuum backfilling method [as described inVaraprasad I].

[0338] Electrical leads were then attached to the mirror. The notch inthe second substrate permitted an electrical lead to be attached at apoint contact on the thin metal film bus bar on the bottom edge of thefirst substrate. Similarly, the notch in the first substrate caused aportion of the top edge of the inward surface of the second substrate tobe exposed, permitting an electrical lead to be attached at a pointcontact on the chromium/silver/tungsten oxide coating.

[0339] Upon introduction of an applied potential of about 1.5 volts tothe mirror, we observed a reflectance change from a high reflectance ofabout 85.3% to a low reflectance of about 7.5%.

Example 18

[0340] In this example, we constructed an aspherical electrochromicmirror cell using as the first substrate a 0.063″ thick clear,HW-ITO-coated glass shape and as the second substrate a 0.093″ thickclear HW-ITO-coated glass substrate. The second substrate was silvercoated on its rear surface (i.e., the fourth surface of the assembly)using a conventional wet chemical silverline process, as is well-knownin the automotive silvering art. The first and second substrates wereindividually bent to an aspheric radius using a multi-radius designcommonly used for driver-side exterior mirrors on vehicles in Europe.This design includes an inboard spherical curvature region of about2,000 mm radius of curvature and a continuously reducing radius,aspherical curvature outboard region that decreased in radius from about560 mm through about 230 mm to about 160 mm. The bent, multi-radiussubstrates were individually press bent, as an oversized lite, in abending press mold, as previously described, by first heating the glassto a temperature of at least about 550° C. followed by press bending toconform to a precision mold.

[0341] After bending and annealing the oversized multi-radius lite, themulti-radius shapes (of the size and shape used as a driver-sideexterior mirror on a Peugeot 605 vehicle manufactured by PSA of Francefor model year 1994), were cut from the oversized, bent, multi-radiuslite. The inward facing, ITO-coated surface of the second substrate wascoated with a layer of tungsten oxide of thickness about 5,500 Å, usingelectron beam evaporation and using a rapid cycle process, as previouslydescribed, whereby evaporation of the tungsten oxide commenced when,during initial pumpdown, the chamber pressure reached about 2×10⁻⁴ torr(mm Hg). The first substrate and the second substrate were positioned inspaced apart relationship to form an interpane spacing of about 88 μmbetween the coated inward facing surfaces of the substrates. The sealmaterial used was EPON 8281 epoxy that was cured with ANCAMINE® 2014FGas a latent curing agent.

[0342] To enhance uniformity and conformity of matching a local radiusof the first substrate to its corresponding local radius on the secondsubstrate, glass beads having a diameter of about 88 μm were included inthe uncured epoxy as well as being sprinkled over the surface of theinward facing surface of the second substrate. Using a computernumerical control (“CNC”) controlled ASYMTEK dispenser and a 20 gaugeneedle, the uncured epoxy was applied around the perimeter of the inwardsurface of the first substrate. The first substrate was then carefullyaligned over the corresponding local radii of the second substrate andwas temporarily affixed thereto using simple clamps. This assembly wasplaced in a “MYLAR” vacuum bag and a vacuum was established so thatatmospheric pressure impressed upon the surfaces of the assembly toforce conformity between the local radii of the first and secondsubstrates. Next, and while under vacuum and thus still underatmospheric pressure, the vacuum bagged assembly was based in an ovenand exposed to a temperature of about 140° C. for a period of time ofabout one hour to cure the epoxy. Once cured, the assembly was removedfrom the oven, the vacuum bag was vented and removed, and the emptycell, so formed, was filled with the electrolyte of Example 1, supra,using vacuum backfilling.

[0343] Once cell fabrication was completed, we introduced a voltage ofabout 1.4 volts to the mirror, and observed the high reflectance tochange from about 74.7% to a low reflectance of about 7.3%. This changein reflectance was achieved rapidly and uniformly with little to nodouble imaging observed.

[0344] This mirror was mounted into a bezel, and installed in a vehicle.The mirror was found to operate for its intended purpose.

[0345] Also, such mirrors showed the environmental, cycle andperformance resilience described supra.

Example 19

[0346] In this example, we constructed a multi-radius mirror, similar tothat described in Example 18, supra. However, in this example the secondsubstrate was non-ITO coated clear glass, and not silverline mirrored onits fourth surface. Instead, its inward facing plain glass surface wasfirst coated with a layer of chromium (adhesion promoter layer) having athickness of about 1,000 Å, followed by a layer of aluminum (reflector)having a thickness of about 2,000 Å, and followed by a layer of tungstenoxide (electrochromic solid film) having a thickness of about 6,000 Å.

[0347] Once cell fabrication was completed, we introduced a voltage ofabout 1.4 volts to the mirror and observed the high reflectance tochange from about 69.7% to a low reflectance of about 6.4%. This changein reflectance was achieved rapidly and uniformly with little to nodouble imaging observed.

Example 20

[0348] The mirror of this example was fabricated generally as describedin Example 3, supra, except that the front substrate was a flatHW-ITO-coated glass shape having a thickness of about 0.043″, withdimensions of about 6.75″×12.7″. In addition, the rear substrate wasflat, plain glass having a thickness of 0.063″ with similar dimensions.The interpane spacing in this mirror construction was about 74 microns.The electrolyte comprised lithium perchlorate (about 0.01 M), lithiumtetrafluoroborate (about 0.04 M), ferrocene (about 0.04 M) and “UVINUL”400 [about 5% (w/v)] dissolved in a solvent combination oftetramethylene sulfone and propylene carbonate [in a ratio of about60:40 (v/v)]. The electrochromic mirror cell so formed was suitable foruse in an exterior mirror assembly on a large, Class 8, Kenworth T600heavy truck manufactured by Kenworth Truck Company, Seattle, Wash.

[0349] Once cell fabrication was completed, we introduced a voltage ofabout 1.4 volts to the mirror (using around-the-perimeter bus bars), andobserved the high reflectance to change from about 81.2% to a lowreflectance of about 16.5%. This change in reflectance was achievedrapidly and uniformly with little to no double imaging observed.

Example 21

[0350] In this example, we report results of rearview mirrorconstructions otherwise similar to that described in Example 1, supra,except for the use of tungsten oxide doped with tin instead of undopedtungsten oxide. Electrochromic solid films of the tin doped tungstenoxide type were deposited both by physical vapor deposition(specifically, electron beam evaporation) and by non-vacuum deposition[specifically, by wet chemical deposition with the dip/fire technique,see U.S. Pat. No. 4,855,161 (Moser)].

[0351] In the physical vapor deposition approach, the procedure andconstruction described in Example 1, supra, was used but withevaporation of a mixture of tungsten oxide/tin oxide (in a ratio ofabout 95:5% w/w) to form a tin-doped tungsten oxide having a thicknessof about 6,000 Å (with the Sn/WO₃ weight ratio in the coating at about0.04). Rearview mirror cells so formed using such evaporated tin dopedtungsten oxide were tested and operated to determine their suitabilityfor use as rearview mirrors in automobiles. These mirrors were found tobe suitable both in terms of performance and in terms ofcycle/environmental resilience.

[0352] Compared to similar mirror cells fabricated using undopedtungsten oxide, but without other intended differences, tin doping ofthe tungsten oxide film produced a noticeably more neutral colorationwhen the mirrors were electrochromically dimmed under applied potential.Also, we found that mixing of tin oxide with the tungsten oxide duringits reactive evaporation under vacuum led to less spitting from theevaporation crucible and facilitated, perhaps due to enhanced electricalconductivity in the inorganic oxide mixture, easier evaporation of themixture to form the oxide film on the glass. This enhances ease ofmanufacturing of electrochromic devices using, for example, a vacuumdeposited, tungsten oxide-based electrochromic film, and the like. Wealso observed a higher bleached state % reflectivity and a faster bleachtime when tin doped tungsten oxide was used compared to undoped tungstenoxide.

[0353] In the non-vacuum deposition approach, a wet chemical, dip/firemethod was used, such as is described in U.S. Pat. No. 4,855,161(Moser), the disclosure of which is hereby incorporated herein byreference. A dipping solution was prepared which comprised about 7.5 wt% tungsten hexachloride, about 2.5 wt % dibutyltin oxide, about 55 wt %ethyl acetate, about 30 wt % isopropanol and about 5 wt % methanol.HW-ITO coated glass substrates were coated with this sol-gel formulationdipping solution by a conventional dip-coating method, and transferredto an oven pre-heated to a temperature of about 120° C. In the oven, theas-dipped coating, having already been air dried, was fired for a periodof time of about 2 hours to produce the desired tin doped tungsten oxidecoating, with the Sn/WO₃ weight ratio being about 0.25.

[0354] Again, rearview mirrors cells were constructed as described inExample 1, supra, except that this dip/fire tin doped tungsten oxidecoating was used.

[0355] The performance characteristics of such rearview mirrors arereported in Tables VI(a) and VI(b) below: TABLE VI(a) Room Temperature,1.5 V, 5 secs/5 secs cycle Transition Times Number of (secs) Cycles % HR% LR 70-20 % 10-60 % Initial 79.7 9.5 5.3 5.9 25,000 76.6 9.3 5.1 5.250,000 77.0 8.9 4.8 4.9 80,000 76.2 8.9 4.7 4.7 120,000  76.0 8.7 4.74.4

[0356] TABLE VI(b) 50° C., 1.5 V, 5 secs/5 secs cycle Transition TimesNumber of (secs) Cycles % HR % LR 70-20% 10-60% Initial 78.7 8.0 4.7 6.225,000 77.2 8.2 4.6 5.6 50,000 77.6 8.1 4.6 5.2 80,000 76.6 7.7 4.7 5.4120,000  75.5 8.1 4.4 5.2

[0357] Sol-gel formulations dipping formulations with different Sn/WO₃weight ratios were coated on transparent conductor coated glasssubstrates. We found desirable a coating with a ratio between about 0.1and about 0.5. Different firing temperatures were also used, and wefound desirable a firing temperature within the range of about 120° C.and 300° C.

Example 22

[0358] In this example, we constructed a continually variabletransmission bandpass filter. The spectral content passed by a bandpassfilter may be electrically attenuated and thus provide user control overnot just the spectral content of radiation (typically, a spectralsub-region band of visible, ultraviolet, near-infrared or infraredelectromagnetic radiation), but also over the intensity of the radiationpassed by the filter. Such bandpass filters are typically of theinterference type comprising multiple thin film layers of determinedthickness and refractive index so as to selectively transmit (andoccasionally reflect) radiation such as incident light. Suchinterference filters have wide applications, such as in the diagnosis ofdisease (by tracing of fluorescent antibodies), spectral radiometry andcolorimetry. Continually variable transmissive and reflective filtersare useful in optical filters, display devices including heads-updisplay devices, the control of automotive lighting sources includingheadlamps, control enhancement filters, laser optic systems and similarapplications. Such variable intensity filters are preferablymedium-band, narrow-band or restricted band filters that permitisolation of wavelength intervals with a bandwidth as low as a fewnanometers (such as, less than about 100 nanometers, and in someapplications less than about 10 nanometers in more spectrally selectiveapplications) without requiring use of dispersion elements (such asprisms and gratings), but with electrically controllable modulation ofthe intensity of light or other radiation which passes therethroughand/or reflects therefrom.

[0359] As an example of such a variable intensity filter, we constructedan electrochromic window element having dimensions of about 2″×2″, suchas is described in Example 5, supra, and attached to the outermost glasssurface thereof a 600 nm medium-band interference filter having abandwidth of about 40 nm, whose % transmission versus wavelength (nm)spectrum is shown as solid curve X in FIG. 17. This filter was fixed tothe glass of the electrochromic window cell using an index matchingoptical adhesive having an index of about 1.5.

[0360] A plot of % transmission versus wavelength for this continuouslyvariable intensity filter is shown in FIG. 17 for voltages applied tothe electrochromic medium within the range of from about 0 volts toabout 1.4 volts. In FIG. 17, light transmission through the band passfilter and the electrochromic window cell with no potential applied isrepresented by curve A. At an applied potential of about 0.3 volts,light transmission through the band pass filter and the electrochromicwindow cell is represented by curve B. At an applied potential of about0.5 volts, light transmission through the band pass filter and theelectrochromic window cell is represented by curve C. At an appliedpotential of about 0.8 volts, light transmission through the band passfilter and the electrochromic window cell is represented by curve D. Atan applied potential of about 1.1 volts, light transmission through theband pass filter and the electrochromic window cell is represented bycurve E. And at an applied potential of about 1.4 volts, lighttransmission through the band pass filter and the electrochromic windowcell is represented by curve F. In Table VII below, the % transmissionat about 600 nanometers is presented in connection with the voltageapplied to the variable intensity filter. TABLE VII Applied Voltage %transmission at about (volts) 600 nm 0 47 0.3 42 0.5 35 0.8 25 1.1 171.4 9

[0361] As seen in FIG. 17, the spectral selectivity is substantiallypreserved as the light intensity is modulated continuously under apotential variably applied to the electrochromic medium.

[0362] Rather than attaching a separate filter to an electrochromic cellas described above, an alternative approach is to deposit aninterference stack of thin film coatings on at least one surface of thesubstrates in the electrochromic cell. In such an arrangement, thetransparent conductor and a metal oxide electrochromic solid film layermay comprise, in combination with other dielectric, semi-conductor andconducting layers, the interference stack that provides spectralselectivity.

Example 23

[0363] The electrochromic mirror cell of this example was constructed asdescribed in Example 4, supra, except that the electrolyte included AMPTas a redox promoter in place of the redox promoter, phenothiazine. AMPTwas synthesized following the procedures described in U.S. Pat. No.4,666,907 (Fortin), the disclosure of which is hereby incorporatedherein by reference.

[0364] The synthesized AMPT was purified by recrystallization frommethanol.

[0365] The elemental analysis of the AMPT was determined to be: C H N SO Calculated (%) 66.40 4.83 5.16 11.82 11.70 Found (%) 66.55 4.76 5.1912.19 11.30

[0366] The electrolyte comprised AMPT (about 0.035 M), ferrocene (about0.02 M), lithium perchlorate (about 0.055 M) and “UVINUL” 400 [about 5%(w/v)] dissolved in propylene carbonate. Performance of the filledelectrochromic mirror cell is reported in Table VIII below: TABLE VIII50° C., 1.3 V, 15 sec/15 sec cycle Number of Transition Times (seconds)Cycles % HR % LR 70-20 60-20 10-60 10-50 Original 74.6 6.7 3.5 3.1 13.67.6 65,000 71.4 8.4 4.1 3.6 5.1 3.6

Example 24

[0367] The electrochromic mirror cell of this example was constructed asdescribed in Example 3, supra, except that the electrolyte included C-PTas a redox promoter in place of the redox promoter, phenothiazine. C-PTwas synthesized following the procedures described in N. L. Smith, J.Org. Chem., 15, 1125 (1950).

[0368] In this example, the substrates were juxtaposed flush to eachother and an around-the-perimeter evaporated bus bar (comprising about1,000 Å of chromium metal) was evaporatively deposited, using a mask tomask off the central portion, around the edge perimeter of the inwardfacing surface of the first ITO-coated substrate followed by another10,000 Å of silver metal evaporated thereover. A chromium adhesionlayer/silver reflector layer/tungsten oxide electrochromic solid filmlayer was evaporated onto the opposing surface of the second substrate,which was plain glass. The electrolyte comprised C-PT (about 0.05 M),lithium perchlorate (about 0.05 M) and “UVINUL” 400 [about 5% (w/v)]dissolved in propylene carbonate.

[0369] With a potential of about 1.3 volts applied between theevaporated bus bar around the perimeter of the inward facing surface ofthe first substrate and the metal reflector layer on the opposing secondsubstrate, we observed the initial high reflectivity state [HR (%)] tobe about 87.3%, which dimmed to a low reflectivity state [LR (%)] ofabout 7.2%, with the transition from 70 to 20% reflectance occurring ina period of time of about 2.1 seconds and the transition from 10 to 60%reflectance, upon bleaching by shorting the electrodes, occurring in aperiod of time of about 7.1 seconds.

Example 25

[0370] In this example, we constructed an electrochromic mirror suitablefor use as an interior rearview mirror for a motor vehicle. Constructionwas otherwise similar to that described in Example 6, supra, except thatthe shape of the mirror constructed for this example was of the size andshape commonly used for interior rearview mirrors. In addition, thefirst substrate was glass coated with a layer of ITO having a thicknessof about 300 Å, with a specific resistivity of about 2.4×10⁻⁴ohm.centimeter and a sheet resistance of about 80 ohms per square. Also,a thin film of aluminum having a thickness of about 2,000 Å was used asa reflective element instead of the silver reflective element used inthe construction of Example 6, supra.

[0371] We filled the electrochromic rearview mirror with an electrolytecomprising ferrocene (about 0.015 M), phenothiazine (about 0.06 M),lithium perchlorate (about 0.05 M) and “UVINUL” 400 [about 5% (w/v)] ina solvent combination of propylene carbonate and tetramethylene sulfone[in a ratio of about 50:50 (v/v)].

[0372] With about 1.1 to about 1.4 volts applied between the wrap-aroundsilver conductive frit bus bar on the perimeter of the ITO-coated,inward facing surface on the first substrate and the aluminumreflector/chromium adhesion layer combination on the opposing surface ofthe second substrate, the electrochromic rearview mirror was observed todim from a high reflectivity state of about 70%±5% reflectance to adimmed state of about 6%±2% reflectance.

[0373] The electrochromic mirror of this example was tested anddemonstrated to meet the requirements for commercial use on vehicles, asboth interior rearview mirrors and exterior rearview mirrors. Also, interms of cycle stability, an electrochromic mirror (which initiallydemonstrated a high reflectivity state of about 70.5% reflectance, andwhich dimmed to a reflectivity of about 7.1% reflectance when apotential of about 1.4 volts was applied thereto) was repetitivelycycled at a temperature of about 50° C. for a total of 39,463 cycles,with each cycle consisting of the introduction of an applied potentialof about 1.4 volts for 15 seconds and an applied potential of zero voltsfor 15 seconds. After cycling was completed, the mirror retained a highreflectivity state of about 68.2% reflectivity, dimmed to about 6.6%reflectivity under an applied potential of about 1.4 volts, andcontinued to be suitable for use on vehicles. Also, after about 14 daysof oven bake at a temperature of about 85° C., a mirror (which initiallyhad a high reflectivity state of about 71.6% reflectance, and whichdimmed to about 7.4% reflectance when an applied potential of about 1.4volts was introduced thereto) exhibited a high reflectivity state ofabout 76.1% reflectance and dimmed to about 8.5% reflectance when about1.4 volts was applied thereto. This mirror continued to be suitable forits intended use on vehicles even after oven bake at 85° C. This mirrorsatisfied the performance requirements and reliability requirements,such as of automobile manufacturers, to be suitable for use within theinterior cabin of an automobile, or for use as an exterior mirror.

[0374] These examples are provided for illustrative purposes only, andit will be clear to those of ordinary skill in the art that changes andmodifications may be practiced within the spirit of the claims whichdefine the scope of the present invention. Thus, the art-skilled willrecognize or readily ascertain using no more than routineexperimentation, that equivalents exist to the embodiments of theinvention described herein. And, it is intended that such equivalents beencompassed by the claims which follow hereinafter.

What we claim is:
 1. An electrochromic rearview mirror for a motorvehicle comprising: (a) a substantially transparent substrate coatedwith a substantially transparent conductive electrode coating on itsinward surface; (b) a substrate positioned in spaced-apart relationshipwith said substrate of (a); (c) a layer of reflective material coatedonto the inward surface of said substrate of (b) or onto a thin film orstack of thin films coated onto the inward surface of said substrate of(b); (d) an electrochromic solid film coated onto said layer ofreflective material of (c), wherein said solid film comprises aninorganic transition metal oxide; (e) a sealing means positioned towardthe peripheral edge of each of said substrate of (a) and said substrateof (b) and sealingly forming a cavity therebetween; (f) an electrolytecomprising a redox reaction promoter, wherein said electrolyte islocated within said cavity to form an electrochromic element; and (g) ameans for introducing an applied potential to said electrochromicelement to controllably cause a variation in the amount of lightreflected from said mirror.
 2. The electrochromic mirror according toclaim 1, wherein said metal oxide is selected from the group consistingof a Group IV-B metal oxide, a Group V-B metal oxide, a Group VI-B metaloxide and combinations thereof.
 3. The electrochromic mirror accordingto claim 2, wherein said metal oxide is doped with a dopant selectedfrom the group consisting of molybdenum, rhenium, tin, rhodium, indium,bismuth, barium, titanium, tantalum, niobium, copper, cerium, lanthanum,zirconium, zinc and nickel.
 4. The electrochromic mirror according toclaim 3, wherein said metal oxide comprises tungsten oxide.
 5. Theelectrochromic mirror according to claim 4, wherein said dopantcomprises a tin dopant.
 6. The electrochromic mirror according to claim1, wherein said sealing means is deposited with a computer numericalcontrol controlled dispenser.
 7. The electrochromic mirror according toclaim 1, wherein said first substrate and said second substrate are bentso as to form a convex mirror.
 8. The electrochromic mirror according toclaim 1, wherein said first substrate and said second substrate are bentso as to form a multi-radius mirror.
 9. The electrochromic mirroraccording to claim 1, wherein said mirror is prepared using a vacuumbagging technique.
 10. The electrochromic mirror according to claim 9,wherein said cavity includes rigid, spacer means.
 11. The electrochromicmirror according to claim 10, wherein said spacer means comprises glassspacer beads.
 12. The electrochromic mirror according to claim 5,wherein said electrochromic solid film is deposited by a non-vacuumdeposition method.
 13. The electrochromic mirror according to claim 12,wherein said non-vacuum deposition method comprises a wet chemicalmethod.
 14. The electrochromic mirror according to claim 13, whereinsaid wet chemical method comprises a dip/fire deposition method.
 15. Theelectrochromic mirror according to claim 1, wherein said layer ofreflective material comprises a silver thin film coating.
 16. Theelectrochromic mirror according to claim 1, wherein said layer ofreflective material comprises an aluminum thin film coating.